gopalswamy (sloppy): 528 papers, Hirsch index 35, Hirsch ratio 0.066. adsauthor "Gopalswamy, N." abstract sloppy @-------------------------------------------------------------------- Title: Coronal Magnetic Field Measurement from EUV Images Made by the Solar Dynamics Observatory Authors: Gopalswamy, Nat; Nitta, Nariaki; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro, Seiji Bibliographic Code: 2012ApJ...744...72G, eprint = 1109.2925 Abstract By measuring the geometrical properties of the coronal mass ejection (CME) flux rope and the leading shock observed on 2010 June 13 by the Solar Dynamics Observatory (SDO) mission's Atmospheric Imaging Assembly we determine the Alfvén speed and the magnetic field strength in the inner corona at a heliocentric distance of ~1.4 Rs. The basic measurements are the shock standoff distance (DeltaR) ahead of the CME flux rope, the radius of curvature of the flux rope (R _c), and the shock speed. We first derive the Alfvénic Mach number (M) using the relationship, DeltaR/R _c = 0.81[(gamma--1) M ² + 2]/[(gamma+1)(M ² -- 1)], where gamma is the only parameter that needed to be assumed. For gamma = 4/3, the Mach number declined from 3.7 to 1.5 indicating shock weakening within the field of view of the imager. The shock formation coincided with the appearance of a type II radio burst at a frequency of ~300 MHz (harmonic component), providing an independent confirmation of the shock. The shock compression ratio derived from the radio dynamic spectrum was found to be consistent with that derived from the theory of fast-mode MHD shocks. From the measured shock speed and the derived Mach number, we found the Alfvén speed to increase from ~140 km s^--1 to 460 km s^--1 over the distance range 1.2-1.5 Rs. By deriving the upstream plasma density from the emission frequency of the associated type II radio burst, we determined the coronal magnetic field to be in the range 1.3-1.5 G. The derived magnetic field values are consistent with other estimates in a similar distance range. This work demonstrates that the EUV imagers, in the presence of radio dynamic spectra, can be used as coronal magnetometers. @-------------------------------------------------------------------- Title: Magnetic Field Strength in the Upper Solar Corona Using White-light Shock Structures Surrounding Coronal Mass Ejections Authors: Kim, R.-S.; Gopalswamy, N.; Moon, Y.-J.; Cho, K.-S.; Yashiro, S. Bibliographic Code: 2011arXiv1112.0288K, eprint = 1112.0288 Abstract To measure the magnetic field strength in the solar corona, we examined 10 fast (> 1000 km/s) limb CMEs which show clear shock structures in SOHO/LASCO images. By applying piston-shock relationship to the observed CME's standoff distance and electron density compression ratio, we estimated the Mach number, Alfven speed, and magnetic field strength in the height range 3 to 15 solar radii (Rs). Main results from this study are: (1) the standoff distance observed in solar corona is consistent with those from a magnetohydrodynamic (MHD) model and near-Earth observations; (2) the Mach number as a shock strength is in the range 1.49 to 3.43 from the standoff distance ratio, but when we use the density compression ratio, the Mach number is in the range 1.47 to 1.90, implying that the measured density compression ratio is likely to be underestimated due to observational limits; (3) the Alfven speed ranges from 259 to 982 km/s and the magnetic field strength is in the range 6 to 105 mG when the standoff distance is used; (4) if we multiply the density compression ratio by a factor of 2, the Alfven speeds and the magnetic field strengths are consistent in both methods; (5) the magnetic field strengths derived from the shock parameters are similar to those of empirical models and previous estimates. @-------------------------------------------------------------------- Title: The Radio Observatory on the Lunar Surface for Solar studies Authors: Lazio, T. Joseph W.; MacDowall, R. J.; Burns, Jack O.; Jones, D. L.; Weiler, K. W.; Demaio, L.; Cohen, A.; Paravastu Dalal, N.; Polisensky, E.; Stewart, K.; Bale, S.; Gopalswamy, N.; Kaiser, M.; Kasper, J. Bibliographic Code: 2011AdSpR..48.1942L Abstract The Radio Observatory on the Lunar Surface for Solar studies (ROLSS) is a concept for a near-side low radio frequency imaging interferometric array designed to study particle acceleration at the Sun and in the inner heliosphere. The prime science mission is to image the radio emission generated by Type II and III solar radio burst processes with the aim of determining the sites at and mechanisms by which the radiating particles are accelerated. Specific questions to be addressed include the following: (1) Isolating the sites of electron acceleration responsible for Type II and III solar radio bursts during coronal mass ejections (CMEs); and (2) Determining if and the mechanism(s) by which multiple, successive CMEs produce unusually efficient particle acceleration and intense radio emission. Secondary science goals include constraining the density of the lunar ionosphere by searching for a low radio frequency cutoff to solar radio emission and constraining the low energy electron population in astrophysical sources. Key design requirements on ROLSS include the operational frequency and angular resolution. The electron densities in the solar corona and inner heliosphere are such that the relevant emission occurs at frequencies below 10 MHz. Second, resolving the potential sites of particle acceleration requires an instrument with an angular resolution of at least 2°, equivalent to a linear array size of approximately 1000 m. Operations would consist of data acquisition during the lunar day, with regular data downlinks. No operations would occur during lunar night.ROLSS is envisioned as an interferometric array, because a single aperture would be impractically large. The major components of the ROLSS array are 3 antenna arms arranged in a Y shape, with a central electronics package (CEP) located at the center. The Y configuration for the antenna arms both allows for the formation of reasonably high dynamic range images on short time scales as well as relatively easy deployment. Each antenna arm is a linear strip of polyimide film (e.g., Kapton™) on which 16 science antennas are located by depositing a conductor (e.g., silver). The antenna arms can be rolled for transport, with deployment consisting of unrolling the rolls. Each science antenna is a single polarization dipole. The arms also contain transmission lines for carrying the radio signals from the science antennas to the CEP. The CEP itself houses the receivers for the science antennas, the command and data handling hardware, and, mounted externally, the downlink antenna.We have conducted two experiments relevant to the ROLSS concept. First, we deployed a proof-of-concept science antenna. Comparison of the impedance of the antenna feed points with simulations showed a high level of agreement, lending credence to the antenna concept. Second, we exposed a sample of space-qualified polyimide film, with a silver coating on one side, to temperature cycling and UV exposure designed to replicate a year on the lunar surface. No degradation of the polyimide film's material or electric properties was found. Both of these tests support the notion of using polyimide-film based antennas.The prime science mission favors an equatorial site, and a site on the limb could simplify certain aspects of the instrument design. A site on the lunar near side is sufficient for meeting the science goals. While the site should be of relatively low relief topography, the entire site does not have to be flat as the fraction of the area occupied by the antenna arms is relatively small (˜0.3%). Further, the antenna arms do not have to lay flat as deviations of ±1 m are still small relative to the observational wavelengths. Deployment could be accomplished either with astronauts, completely robotically, or via a combination of crewed and robotic means.Future work for the ROLSS concept includes more exhaustive testing of the radio frequency (RF) and environmental suitability of polyimide film-based science antennas, ultra-low power electronics in order to minimize the amount of power storage needed, batteries with a larger temperature range for both survival and operation, and rovers (robotic, crewed, or both) for deployment.The ROLSS array could also serve as the precursor to a larger array on the far side of the Moon for astrophysical and cosmological studies. @-------------------------------------------------------------------- Title: Relation Between the 3D-Geometry of the Coronal Wave and Associated CME During the 26 April 2008 Event Authors: Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2011SoPh..273..421T, eprint = 1103.0196 Abstract We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of ˜ 240 km s^-1. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B observations. We find that the wave structure is asymmetric with an inclination toward East. The associated CME has a deprojected speed of ˜ 750±50 km s^-1, and it shows a non-radial outward motion toward the East with respect to the underlying source region location. Applying the forward fitting model developed by Thernisien, Howard, and Vourlidas (Astrophys. J. 652, 763, 2006), we derive the CME flux rope position on the solar surface to be close to the dimming regions. We conclude that the expanding flanks of the CME most likely drive and shape the coronal wave. @-------------------------------------------------------------------- Title: Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5 Authors: Gopalswamy, Nat; Davila, Joseph M.; Auchère, Frédéric; Schou, Jesper; Korendyke, Clarence M.; Shih, Albert; Johnston, Janet C.; MacDowall, Robert J.; Maksimovic, Milan; Sittler, Edward; Szabo, Adam; Wesenberg, Richard; Vennerstrom, Suzanne; Heber, Bernd Bibliographic Code: 2011SPIE.8148E..30G Abstract Coronal mass ejections (CMEs) and corotating interaction regions (CIRs) as well as their source regions are important because of their space weather consequences. The current understanding of CMEs primarily comes from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions, but these missions lacked some key measurements: STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer. SOHO and other imagers such as the Solar Mass Ejection Imager (SMEI) located on the Sun-Earth line are also not well-suited to measure Earth-directed CMEs. The Earth-Affecting Solar Causes Observatory (EASCO) is a proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be implemented. The study found that the scientific payload (seven remote-sensing and three in-situ instruments) can be readily accommodated and can be launched using an intermediate size vehicle; a hybrid propulsion system consisting of a Xenon ion thruster and hydrazine has been found to be adequate to place the payload at L5. Following a 2-year transfer time, a 4-year operation is considered around the next solar maximum in 2025. @-------------------------------------------------------------------- Title: Factors Affecting The Intensity of Solar Energetic Particle Events Authors: Gopalswamy, Nat Bibliographic Code: 2011arXiv1109.2933G, eprint = 1109.2933 Abstract This paper updates the influence of environmental and source factors of shocks driven by coronal mass ejections (CMEs) that are likely to influence the solar energetic particle (SEP) events. The intensity variation due to CME interaction reported in [1] is confirmed by expanding the investigation to all the large SEP events of solar cycle 23. The large SEP events are separated into two groups, one associated with CMEs running into other CMEs, and the other with CMEs running into the ambient solar wind. SEP events with CME interaction generally have a higher intensity. New possibilities such as the influence of coronal holes on the SEP intensity are also discussed. For example, the presence of a large coronal hole between a well-connected eruption and the solar disk center may render the shock poorly connected because of the interaction between the CME and the coronal hole. This point is illustrated using the 2004 December 3 SEP event delayed by about 12 hours from the onset of the associated CME. There is no other event at the Sun that can be associated with the SEP onset. This event is consistent with the possibility that the coronal hole interaction influences the connectivity of the CMEs that produce SEPs, and hence the intensity of the SEP event. @-------------------------------------------------------------------- Title: Energetic storm particle events in coronal mass ejection-driven shocks Authors: Mäkelä, P.; Gopalswamy, N.; Akiyama, S.; Xie, H.; Yashiro, S. Bibliographic Code: 2011JGRA..11608101M Abstract We investigate the variability in the occurrence of energetic storm particle (ESP) events associated with shocks driven by coronal mass ejections (CMEs). The interplanetary shocks were detected during the period from 1996 to 2006. First, we analyze the CME properties near the Sun. The CMEs with an ESP-producing shock are faster ($\langle$V_CME$\rangle$ = 1088 km/s) than those driving shocks without an ESP event ($\langle$V_CME$\rangle$ = 771 km/s) and have a larger fraction of halo CMEs (67% versus 38%). The Alfvénic Mach numbers of shocks with an ESP event are on average 1.6 times higher than those of shocks without. We also contrast the ESP event properties and frequency in shocks with and without a type II radio burst by dividing the shocks into radio-loud (RL) and radio-quiet (RQ) shocks, respectively. The shocks seem to be organized into a decreasing sequence by the energy content of the CMEs: RL shocks with an ESP event are driven by the most energetic CMEs, followed by RL shocks without an ESP event, then RQ shocks with and without an ESP event. The ESP events occur more often in RL shocks than in RQ shocks: 52% of RL shocks and only ˜33% of RQ shocks produced an ESP event at proton energies above 1.8 MeV; in the keV energy range the ESP frequencies are 80% and 65%, respectively. Electron ESP events were detected in 19% of RQ shocks and 39% of RL shocks. In addition, we find that (1) ESP events in RQ shocks are less intense than those in RL shocks; (2) RQ shocks with ESP events are predominately quasi-perpendicular shocks; (3) their solar sources are located slightly to the east of the central meridian; and (4) ESP event sizes show a modest positive correlation with the CME and shock speeds. The observation that RL shocks tend to produce more frequently ESP events with larger particle flux increases than RQ shocks emphasizes the importance of type II bursts in identifying solar events prone to producing high particle fluxes in the near-Earth space. However, the trend is not definitive. If there is no type II emission, an ESP event is less likely but not absent. The variability in the probability and size of ESP events most likely reflects differences in the shock formation in the low corona and changes in the properties of the shocks as they propagate through interplanetary space and the escape efficiency of accelerated particles from the shock front. @-------------------------------------------------------------------- Title: The Brazilian decimetric array and space weather Authors: Sawant, Hanumant S.; Gopalswamy, Natchimuthuk; Rosa, Reinaldo R.; Sych, Robert A.; Anfinogentov, Sergey A.; Fernandes, Francisco C. R.; Cecatto, José R.; Costa, Joaquim E. R. Bibliographic Code: 2011JASTP..73.1300S Abstract We report on the development and current status of the Brazilian Decimetric Array (BDA), which will play a vital role in filling the existing gaps in imaging the Sun at decimetric wavelengths. The BDA will operate in the following radio bands: 1.2-1.7, 2.8, and 5.6 GHz with high spatial and temporal resolutions. BDA can observe flares and coronal mass ejections (CMEs) in a spectral range poorly covered in the past, thus providing important information to space weather science. The smallest baseline of 9 m employed by the BDA combined with high sensitivity will readily identify large-scale structures such as coronal holes and provide information on wave flows from them. New methods are being developed to analyze the solar-disk data with high time resolution by using tomographic and spatial PWF techniques that can readily identify coronal holes in their initial stage. Efforts are also being made to analyze the BDA data in real time in conjunction with SOHO data for a better understanding of CMEs and coronal holes. This paper provides a brief description of the BDA, and the new techniques of data analysis. @-------------------------------------------------------------------- Title: The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-driven Shock Authors: Gopalswamy, Nat; Yashiro, Seiji Bibliographic Code: 2011ApJ...736L..17G, eprint = 1106.4832 Abstract We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfvén Mach number, and hence the Alfvén speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from ~48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances. @-------------------------------------------------------------------- Title: Effects of Refraction on Angles and Times of Arrival of Solar Radio Bursts Authors: Thejappa, G.; MacDowall, R. J.; Gopalswamy, N. Bibliographic Code: 2011ApJ...734...16T Abstract Solar type III and type II radio bursts suffer severe bending and group delay due to refraction while escaping from the source where the refractive index mu can be as low as ~0 to the observer where mu ~ 1. These propagation effects can manifest themselves as errors in the observed directions and times of arrival at the telescope. We describe a ray-tracing technique that can be used to estimate these errors. By applying this technique to the spherically symmetric density model derived using the data from the WIND/Waves experiment, we show that (1) the fundamental and harmonic emissions escape the solar atmosphere in narrow cones (at 625 kHz the widths of these escape cones are ~1fdg1 and ~8°, respectively), (2) the errors in the angles as well as the times of arrival increase monotonically with the angle of arrival (at 625 kHz these errors are 0fdg26 and ~17.2 s for the fundamental and ~0fdg52 and ~7.6 s for the harmonic at the maximum possible angles of arrival of ~0fdg55 and ~4°, respectively), and (3) the lower the frequencies are, the higher the errors in both the angles and times of arrival are. This implies that at 625 kHz the measured arrival angles and arrival times of the fundamental and harmonic are off by ~50% and ~13%, and ~3.4% and ~1.5%, respectively. @-------------------------------------------------------------------- Title: What Controls the Classification of Interplanetary Mass Ejections Authors: Moon, Yong-Jae; Gopalswamy, N.; Kim, R.; Xie, H.; Yashiro, S. Bibliographic Code: 2011SPD....42.2401M Abstract In this paper we address a question what controls the classification of interplanetary mass ejections (ICMEs): magnetic cloud (MC) or ejecta (EJ). Using 186 shock-associated ICMEs from 1997 to 2006, we have examined three possible causes: (1) magnetic complexity with a proxy of sunspot number, (2) CME direction as a proxy of cone angle (the angle between the CME cone axis and the plane of sky), and (3) ICME-ICME interaction with a proxy of the number of halo CMEs. First, the fraction of MC is poorly anti-correlated (R=-0.36) with annual sunspot number. Second, the distribution of CME cone angle for 38 EJs is not much different from that for 16 MCs. Third, the annual fraction of magnetic cloud is well anti-correlated (R=-0.78) with the annual number of halo CMEs. To demonstrate such a relationship, we consider all halo CMEs during the same period and statistically searched the candidate of interacting ICMEs according to temporal and spatial closeness. As a result, we find that the annual fraction of interacting ICME candidates is well correlated (R=0.87) with the annual number of the halo CMEs as well as anti-correlated (R=-0.85) with the annual fraction of MCs. The contingency table between ICME-ICME interaction and MC occurrence also shows a good statistical result: Hit (110), False Alarm (53), Prediction of detection 'yes' (0.88), and Critical Success Index (0.62). Our results imply that the interaction of ICMEs is mainly responsible for their classification. @-------------------------------------------------------------------- Title: The 2011 February 15 Coronal Mass Ejection: Reconciling SOHO and STEREO Observations in Quadrature Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Kaiser, M. L. Bibliographic Code: 2011SPD....42.2322G Abstract The Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO observed a fast halo coronal mass ejection on 2011 February 15. The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth by 87 deg and STEREO-B 94 deg behind Earth), enabling CME measurement using the three spacecraft. The sky-plane speed measured by SOHO/LASCO is closely related to the expansion speed of the CME, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp) and radial speed (Vrad) derived previously from geometrical considerations (Gopalswamy et al. 2009): = Vrad = ½ (1 + cot w) Vexp, where w is the half width of the CME. We can also measure the Earthward speed of the CME directly from the STEREO measurements. The travel time to Earth predicted from the Earthward speed using the Empirical Shock Arrival model is 12 hours shorter than the actual travel time obtained from in situ measurements at L1. The primary reason for this discrepancy seems to be the interaction with the two preceding CMEs that slowed down the CME in question. The CME interaction is also confirmed from the radio enhancement observed by Wind/WAVES and STEREO WAVES experiments. @-------------------------------------------------------------------- Title: Comparison between Linear and Quadratic Drag Models for ICME Propagation Authors: Moon, Yong-Jae; Vrsnak, B.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2011SPD....42.2318M Abstract In this paper, we have examined a recent issue what kinds of drag form (linear or quadratic drag) is proper for interplanetary coronal mass ejections (ICMEs). For this work, we have examined well-observed LASCO CMEs associated with DH Type II bursts satisfying the following conditions: (1) the CMEs speeds are larger than 600 km/s, (2) their longitudes are larger than 60 degrees, (3) the numbers of their LASCO data points are larger than 6, and (4) their accelerations are smaller than -1 m/s². We find that their accelerations (Log a) in the LASCO field of view has a very good quadratic relationship with the CME relative speeds Log (Vcme-400) with the correlation coefficient of R=0.83, supporting the quadratic drag force. Another test has been made by applying two drag models to two well-observed STEREO/SECCHI events. As a result, we found that (1) while two speed profiles are well fitted by the quadratic drag model, one speed profile can not be fitted by the linear model; (2) while the physical parameters for the quadratic model are well consistent with observations, the kinematic viscosity for the linear model should be four orders larger than its observed value. From this study, we conclude that the quadratic drag model for ICME propagation should be proper than the linear drag model. @-------------------------------------------------------------------- Title: Association of EUV Waves and Coronal Mass Ejections Authors: Yashiro, Seiji; Gopalswamy, N. Bibliographic Code: 2011SPD....42.2317Y Abstract The association between EUV waves and coronal mass ejections (CMEs) is difficult to establish for disk flares using observations from the Sun-Earth line because of visibility issues. The other possibility is the real absence of mass motion in flares. This issue can be effectively addressed by the twin spacecraft of the Solar Terrestrial Relations Observatory (STEREO) mission. The Ahead and Behind spacecraft of the STEREO mission were located around ±90° from the Sun-Earth line from 2010 to 2012. This is the first opportunity to investigate the connection between CMEs and EUV waves with a high degree of accuracy. During January 28 - March 9, 2011, two X- and 28 M-class flares occurred. We examined their CME associations using STEREO/SECCHI and SOHO/LASCO observations, and EUV wave associations using SDO/AIA data. We found that 10 out of 30 flares were associated with clear flux-rope CMEs (FRCMEs) while 16 did not have any erupting features above the flaring regions in the coronagraph images. The remaining four flares had narrow CMEs or outflow above the flaring regions but their connection to the flares is unclear. We also found all of the FRCME-associated flares had clear EUV waves, while the flares without CMEs also lacked EUV waves. We found one-to-one correspondence between EUV waves and FRCMEs. @-------------------------------------------------------------------- Title: Source of Coronal and IP Type II Bursts Inferred from Radio and White-light Observations Authors: Makela, Pertti; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2011SPD....42.2316M Abstract We report on a study of the speeds of type II radio bursts in the metric (m) and dekameter-hectometric (DH) wavelength range constrained by the time-height measurements of the associated coronal mass ejections (CMEs). Dynamic spectra of type II bursts show occasionally a clear discontinuity in frequency and temporal overlap of metric and DH type II bursts. This has been interpreted to signify either (1) a different origin of the type II components, i.e., the DH-component is caused by a CME-driven shock and the m-component by a blast wave or unknown source, or (2) same source but a different location, i.e., the DH-component originates from the shock nose and the m-component from the shock flanks. Our preliminary results suggest that the single CME-driven shock scenario can match both m and DH-component of type II bursts reasonably well, assuming that true space speeds of the CMEs and shocks are utilized. @-------------------------------------------------------------------- Title: Understanding Interplanetary Shock Dynamics In The Inner Heliosphere:The 2010 April 03 and August 01 Events Authors: Xie, Hong; May, L.; St Cyr, C. O.; Gopalswamy, N.; Odstrcil, D.; Cremades, H. Bibliographic Code: 2011SPD....42.2312X Abstract The 2010 April 03 and 2010 August 01 CMEs were studied using observations from STEREO A and B, and SOHO LASCO, combined with ENLIL+Cone model simulations preformed at the Community Coordinated Modelling Center (CCMC). In particular, we identified the origin of CMEs using STEREO EUVI and/or SDO images. A flux-rope model fitting to the SECCHI A and B, SOHO/LASCO images was used to determine CME directions and actual speeds. J-maps from COR2/HI-1/HI-2 and simulations from CCMC were used to study the formation and evolution of the shocks in the inner heliosphere. We compared the simulation results with the observed height-time profiles of the shock from white light and kilometric type II (KmTII) burst (Wind/WAVES) observations. The predicted shock arrival at Earth is compared with in-situ observations from ACE. It is found that that ENLIL+cone model predicts the kinematics of shock evolution well for both cases and the KmTII method is more successful when using ENLIL model plasma density. @-------------------------------------------------------------------- Title: Cme Evolution In The Interplanetary Space Based On Stereo Observations. Authors: Poomvises, Watanachak; Gopalswamy, N.; Zhang, J. Bibliographic Code: 2011SPD....42.2311P Abstract STEREO/SECCHI observations help identify the true 3-D geometric structure of CMEs and track their true evolution in the inner heliosphere. Using STEREO observations, it is possible to obtain the true speed of CMEs, which is key in predicting the arrival time of CMEs at Earth (Gopalswamy et al. 2001). From the STEREO data, we are able to track and measure CMEs in 3-D by using Raytrace model (Thernisien et al 2006, 2009), which is free from projection effects and thus result in true CME velocities. Studied study 5 CME events, we found that the acceleration/deceleration of CMEs occur within 50 Rs from the Sun, after that the CME velocity converges to the narrow range (Poomvises et al 2010). Additionally, we found that expansion velocity of CMEs also converges to a narrow range after 50 Rs. The observations are consistent with the theoretical flux rope model. The CME evolution can be explained by different forces that act on the CME: Lorentz force, thermal pressure force, gravity force, aero-dynamic drag force, and the magnetic drag force. The drag coefficient typically varies between 2.5 to 3.0, which is much smaller than the factor of twelve suggested by earlier studies. Moreover, the value of the polytropic index has been found to be between 1.35 to 1.60. Therefore, we have been able to narrow down the range of values for the drag coefficient and the polytropic index, which help in improve the prediction of CME travel time. @-------------------------------------------------------------------- Title: Halo Coronal Mass Ejections: Comparing Observations to Models Authors: Gilbert, Holly; Orlove, M.; St. Cyr, O.; Xie, H.; Mays, L. M.; Gopalswamy, N. Bibliographic Code: 2011SPD....42.2310G Abstract Since 1996, the SOHO LASCO coronagraphs have detected "halo'' CMEs that appear to be directed toward Earth, but information about the size and speed of these events seen face-on has been limited. From a single vantage point along the Sun-Earth line, the primary limitation has been ambiguity in fitting the cone model (or other forward-modeling techniques, e.g., Thernisian et al., 2006). But in the past few years, the STEREO mission has provided a view of Earth-directed events from the side. These events offer the opportunity to compare measurements (width and speed) of halo CMEs observed by STEREO with models that derive halo CME properties. We report here results of such a comparison on a large sample of LASCO CMEs in the STEREO era. @-------------------------------------------------------------------- Title: Magnetic Field Strength in the Upper Solar Corona Using White-light Shock Structures Surrounding Coronal Mass Ejections Authors: Kim, Roksoon; Gopalswamy, N.; Moon, Y.; Cho, K.; Yashiro, S. Bibliographic Code: 2011SPD....42.2306K Abstract To measure the magnetic field strength in the solar corona, we examined 12 fast (> 1000 km s-1) limb CMEs which show clear shock-like structures in SOHO/LASCO observations. By applying piston-shock relationship to the observed CME's standoff distance and electron density compression ratio, we estimated the Mach number, Alfven speed, and magnetic field strength in the height range 3 to 15Rs. Main results from this study are: (1) the standoff distance observed in the solar corona is consistent with those from a magnetohydrodynamic (MHD) model and near-Earth observations; (2) the Mach number as a shock strength is in the range 1.49 to 3.52 from the standoff distance data, but when we use the compression ratio, the Mach number is in the range 1.47 to 1.90, implying that the measured density compression ratio is likely to be underestimated due to projection effects; (3) the Alfven speeds range from 259 to 982 km s-1 and the magnetic field strength is in the range 0.04 to 0.35 G when the standoff distance is used; (4) if we multiply the compression ratio by a factor of 2, the Alfven speeds and the magnetic field strengths are consistent in both methods; (5) the derived magnetic field strengths in the inner corona are similar to those of empirical models but noticeably higher in the upper corona. This is a new attempt to measure magnetic field strength from coronagraph observation alone. These observations are consistent with the idea that the diffuse structures surrounding the CME front can be interpreted as shock structures. @-------------------------------------------------------------------- Title: Earth-Affecting Solar Causes Observatory (EASCO): Results of the Mission Concept Study Authors: Gopalswamy, N.; EASCO Team Bibliographic Code: 2011SPD....42.1518G Abstract Coronal mass ejections (CMEs) corotating interaction regions (CIRs) are two large-scale structures that originate from the Sun and affect the heliosphere in general and Earth in particular. While CIRs are generally detected by in-situ plasma signatures, CMEs are remote-sensed when they are still close to the Sun. The current understanding of CMEs primarily come from the SOHO and STEREO missions. In spite of the enormous progress made, there are some serious deficiencies in these missions. For example, these missions did not carry all the necessary instruments (STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer). From the Sun-Earth line, SOHO was not well-suited for observing Earth-directed CMEs because of the occulting disk. STEREO's angle with the Sun-Earth line is changing constantly, so only a limited number of Earth-directed CMEs were observed in profile. In order to overcome these difficulties, we proposed a news L5 mission concept known as the Earth-Affecting Solar Causes Observatory (EASCO). The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center. The aim of the MDL study was to see how the scientific payload consisting of ten instruments can be accommodated in the spacecraft bus, what propulsion system can transfer the payload to the Sun-Earth L5, and what launch vehicles are appropriate. The study found that all the ten instruments can be readily accommodated and can be launched using an intermediate size vehicle such as Taurus II with enhanced faring. The study also found that a hybrid propulsion system consisting of an ion thruster (using 55 kg of Xenon) and hydrazine ( 10 kg) is adequate to place the payload at L5. The transfer will take about 2 years and the science mission will last for 4 years around the next solar maximum in 2025. @-------------------------------------------------------------------- Title: A Radio Observatory on the Lunar Surface for Solar studies (ROLSS) Authors: MacDowall, R. J.; Lazio, T. J.; Bale, S. D.; Burns, J.; Farrell, W. M.; Gopalswamy, N.; Jones, D. L.; Weiler, K. W. Bibliographic Code: 2011arXiv1105.0666M, eprint = 1105.0666 Abstract By volume, more than 99% of the solar system has not been imaged at radio frequencies. Almost all of this space (the solar wind) can be traversed by fast electrons producing radio emissions at frequencies lower than the terrestrial ionospheric cutoff, which prevents observation from the ground. To date, radio astronomy-capable space missions consist of one or a few satellites, typically far from each other, which measure total power from the radio sources, but cannot produce images with useful angular resolution. To produce such images, we require arrays of antennas distributed over many wavelengths (hundreds of meters to kilometers) to permit aperture synthesis imaging. Such arrays could be free-flying arrays of microsatellites or antennas laid out on the lunar surface. In this white paper, we present the lunar option. If such an array were in place by 2020, it would provide context for observations during Solar Probe Plus perihelion passes. Studies of the lunar ionosphere's density and time variability are also important goals. This white paper applies to the Solar and Heliospheric Physics study panel. @-------------------------------------------------------------------- Title: Earth-Affecting Solar Causes Observatory (EASCO): A potential International Living with a Star Mission from Sun-Earth L5 Authors: Gopalswamy, N.; Davila, J. M.; St. Cyr, O. C.; Sittler, E. C.; Auchère, F.; Duvall, T. L.; Hoeksema, J. T.; Maksimovic, M.; MacDowall, R. J.; Szabo, A.; Collier, M. R. Bibliographic Code: 2011JASTP..73..658G Abstract This paper describes the scientific rationale for an L5 mission and a partial list of key scientific instruments the mission should carry. The L5 vantage point provides an unprecedented view of the solar disturbances and their solar sources that can greatly advance the science behind space weather. A coronagraph and a heliospheric imager at L5 will be able to view CMEs broadsided, so space speed of the Earth-directed CMEs can be measured accurately and their radial structure discerned. In addition, an inner coronal imager and a magnetograph from L5 can give advance information on active regions and coronal holes that will soon rotate on to the solar disk. Radio remote sensing at low frequencies can provide information on shock-driving CMEs, the most dangerous of all CMEs. Coordinated helioseismic measurements from the Sun-Earth line and L5 provide information on the physical conditions at the base of the convection zone, where solar magnetism originates. Finally, in situ measurements at L5 can provide information on the large-scale solar wind structures (corotating interaction regions (CIRs)) heading towards Earth that potentially result in adverse space weather. @-------------------------------------------------------------------- Title: Relation Between the 3D-Geometry of the Coronal Wave and Associated CME During the 26 April 2008 Event Authors: Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2011SoPh..tmp..158T Abstract We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of ˜ 240 km s^-1. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B observations. We find that the wave structure is asymmetric with an inclination toward East. The associated CME has a deprojected speed of ˜ 750±50 km s^-1, and it shows a non-radial outward motion toward the East with respect to the underlying source region location. Applying the forward fitting model developed by Thernisien, Howard, and Vourlidas (Astrophys. J. 652, 763, 2006), we derive the CME flux rope position on the solar surface to be close to the dimming regions. We conclude that the expanding flanks of the CME most likely drive and shape the coronal wave. @-------------------------------------------------------------------- Title: Maximum Coronal Mass Ejection Speed as an Indicator of Solar and Geomagnetic Activities Authors: Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Gopalswamy, N.; Ozguc, A.; Rozelot, J. P. Bibliographic Code: 2011ApJ...727...44K, eprint = 1111.4000 Abstract We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions. @-------------------------------------------------------------------- Title: The International Space Weather Initiative (ISWI) Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.; Bogdan, Tom; Hapgood, Mike Bibliographic Code: 2011sswh.book..375D Abstract @-------------------------------------------------------------------- Title: Universal Heliophysical Processes Authors: Gopalswamy, Nat Bibliographic Code: 2011sswh.book....9G Abstract @-------------------------------------------------------------------- Title: Mukul Ranjan Kundu Authors: Gopalswamy, Nat Bibliographic Code: 2011PhT....64d..71G Abstract @-------------------------------------------------------------------- Title: Low-frequency type III radio bursts and solar energetic particle events Authors: Gopalswamy, N.; Mäkelä, P. Bibliographic Code: 2011CEAB...35...71G Abstract Complex type III bursts at low-frequencies (<14 MHz) are thought to indicate large solar energetic particle (SEP) events. We analysed six complex type III bursts from the same active region, one of which was not accompanied by a SEP event. This event was accompanied by a fast and wide coronal mass ejection (CME), but lacked a type II burst and an interplanetary shock. When we examined the evolution and the magnetic configuration of the active region, we did not find anything peculiar. The lowest frequency of type III emission occurred at the local plasma frequency in the vicinity of the Wind spacecraft that observed the type III, which confirms that the magnetic connectivity of the source region was good. We conclude that the lack of SEPs is due to the lack of production rather than due to poor magnetic connectivity. We also show that neither the type III burst duration nor the burst intensity was able to distinguish between SEP and non-SEP events. The lack of SEP event can be readily explained under the shock-acceleration paradigm, but not under the flare-acceleration paradigm. @-------------------------------------------------------------------- Title: International Space Weather Initiative (ISWI) Authors: Gopalswamy, N.; Davila, J. M. Bibliographic Code: 2010nspm.conf..160G Abstract The International Space Weather Initiative (ISWI) is an international scientific program to understand the external drivers of space weather. The science and applications of space weather has been brought to prominence because of the rapid development of space based technology that is useful for all human beings. The ISWI program has its roots in the successful International Heliophysical Year (IHY) program that ran during 2007 - 2009. The primary objective of the ISWI program is to advance the science space weather by a combination of instrument deployment, analysis and interpretation of space weather data from the instruments deployed in conjunction with space data, and communicate the results to the public and students. Like the IHY, the ISWI will be a grass roots organization with key participation from national coordinators with cooperation in an international steering committee. This talk outlines the ISWI program including its organization and proposed activities. @-------------------------------------------------------------------- Title: Corona Mass Ejections: a Summary of Recent Results Authors: Gopalswamy, N. Bibliographic Code: 2010nspm.conf..108G Abstract Corona mass ejections (CMEs) have been Recognized as the most energetic phenomenon in the heliosphere, deriving their energy from the stressed magnetic fields on the Sun. This paper highlights some of the recent results obtained on CMEs from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions. The summary of follows the talk. SOHO observations revealed that the CME rate is almost a factor of: Two larger than previously thought and varied with the solar activity cycle in a complex way (eg, high-latitude CMEs occurred in great abundance during the solar years maximum). CMEs were found to interact with other CMEs as well as with other large-scale structures (corona holes), Resulting in deflections and additional particle acceleration. STEREO observations have confirmed the three-dimensional nature of CMEs and shocks the surrounding them. The EUV signatures (flare arcades, Corona dimming, filament Eruption, and EUV waves) associated with CMEs have become vital in the identification of sources from Which solar CMEs erupt. CMEs with speeds exceeding the characteristic speeds of the corona and the interplanetary medium drive shocks, which produce type II radio bursts. The wavelength range of type II bursts depends on the CME kinetic energy: type II bursts with emission components at all wavelengths (metric to kilometric) due to CMEs are of the highest kinetic energy. Some CMEs, as fast as 1600 km / s do not produce type II bursts, while slow CMEs (400 km / s) occasionally produce type II bursts. These observations can be explained as the variation in the ambient flow speed (solar wind) speed and the Alfvén. Not all CME-driven shocks produce type II bursts because they are either subcritical Or do not have the appropriate geometry. The same shocks that produce type II bursts also produce solar energetic particles (SEPS), Whose release near the Sun seems to be delayed with respect to the onset of type II bursts. This may indicate a subtle difference in the acceleration of the ions and ~ 10 keV electrons needed to produce type II bursts. Surprisingly, some shocks lacking type II bursts are associated with energetic storm particle events (ESPs), pointing to the importance of electron escape from the shock for producing the radio emission. CMEs slow down or accelerate in the interplanetary medium because of the drag force, which modifies the transit time of CMEs and shocks. Halo CMEs that appear to surround the occulting disk were known before the SOHO era, and occasional events. During the SOHO era, they became very prominent because of their ability to impact Earth and producing geomagnetic storms. Halo CMEs are generally more energetic than ordinary CMEs, which means they can produce north of the impact on Earth's magnetosphere. Their origin close to the center disk of the Sun ensures direct impact on the magnetosphere, although their internal magnetic structure is crucial in causing storms. The solar sources of CMEs that produce SEP events at Earth, on the other hand, are generally in the western hemisphere because of the magnetic connectivity. Thus, CMEs are very interesting from the point of view of plasma physics as well as practical implications because of their space weather impact. @-------------------------------------------------------------------- Title: Aspects of Coronal Mass Ejections Related to Space Weather Authors: Gopalswamy, N. Bibliographic Code: 2010AGUFMSH52A..03G Abstract Solar cycle 23 witnessed an unprecedented array of space- and ground-based instruments observing the violent eruptions from the Sun that had huge impact on the heliosphere. It was possible to characterize coronal mass ejections (CMEs) that cause extreme solar energetic particle events and geomagnetic storms, the two aspects that concern the space weather community. In this paper I discuss the special populations of CMEs that have significant interplanetary consequences: shock-driving CMEs identified based on their association with type II radio bursts and in-situ shocks, SEP-producing CMEs, and geoeffective CMEs (those that produce geomagnetic storms). I discuss the kinematic and solar-source properties of these populations and how they vary with the solar activity cycle. I also compare their properties with the general population of CMEs, so one can recognize when and where these events occur on the Sun. @-------------------------------------------------------------------- Title: Relation between CME Speed and Magnetic Helicity in Solar Source Regions Authors: Jung, H.; Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Xie, H. Bibliographic Code: 2010AGUFMSH51C1686J Abstract Coronal mass ejections (CMEs) are thought to be powered by the free energy in the solar source regions. The magnetic helicity in the source regions is one of the indicators of this free energy. In order to see the relationship between the magnetic helicity of CME source regions and CME energy, we considered a set of 41 solar source regions (from solar cycle 23) from which CMEs erupted and ended up as magnetic clouds near Earth. Using EUV and magnetogram data from the Solar and Heliospheric Observatory (SOHO) mission, we determined the most probable linear force-free magnetic structure and its magnetic helicity for each CME source region. The magnetograms taken just prior to the CME eruption were used to compute the magnetic helicity. The CME speeds were obtained from the SOHO/LASCO CME catalog (http://cdaw.gsfc.nasa.gov). We found that the magnetic helicity is positively correlated with the speed of CMEs. This result suggests that the magnetic helicity of CME source regions maybe useful for predicting CME speed. @-------------------------------------------------------------------- Title: Radio-Loud Coronal Mass Ejections without Shocks near Earth Authors: Akiyama, S.; Gopalswamy, N.; Xie, H.; Yashiro, S.; Makela, P. A.; St Cyr, O. C.; MacDowall, R. J.; Kaiser, M. L. Bibliographic Code: 2010AGUFMSH32A..07A Abstract Type II radio bursts are produced by low energy electrons accelerated in shocks driven by coronal mass ejections (CMEs). One can infer shocks near the Sun, in the Interplanetary medium, and near Earth depending on the wavelength range in which the type II bursts are produced. In fact, type II bursts are good indicators of CMEs that produce solar energetic particles. If the type II burst occurs from a source on the Earth-facing side of the solar disk, it is highly likely that a shock arrives at Earth in 2-3 days and hence can be used to predict shock arrival at Earth. However, a significant fraction of CMEs producing type II bursts were not associated shocks at Earth, even though the CMEs originated close to the disk center. There are several reasons for the lack of shock at 1 AU. CMEs originating at large central meridian distances (CMDs) may be driving a shock, but the shock may not be extended sufficiently to reach to the Sun-Earth line. Another possibility is CME cannibalism because of which shocks merge and one observes a single shock at Earth. Finally, the CME-driven shock may become weak and dissipate before reaching 1 AU. We examined a set of 30 type II bursts observed by the Wind/WAVES experiment that had the solar sources very close to the disk center (within a CMD of 15 degrees), but did not have shock at Earth. We find that the near-Sun speeds of the associated CMEs average to ~600 km/s, only slightly higher than the average speed of CMEs associated with radio-quiet shocks. However, the fraction of halo CMEs is only ~28%, compared to 40% for radio-quiet shocks and 72% for all radio-loud shocks. We conclude that the disk-center radio loud CMEs with no shocks at 1 AU are generally of lower energy and they drive shocks only close to the Sun. @-------------------------------------------------------------------- Title: Understanding Interplanetary Shock Dynamics in the Inner Heliosphere with New Observations and Modeling Techniques: Case studies on the 2010-04-03 and 2010-08-01 events Authors: Xie, H.; Mays, L.; St Cyr, O. C.; Gopalswamy, N.; Odstrcil, D.; Cremades, H. Bibliographic Code: 2010AGUFMSH23B1858X Abstract The 2010 April 03 and August 01 CMEs were studied using observations from STEREO A and B, and SOHO LASCO, combined with ENLIL+Cone model simulations preformed at the Community Coordinated Modelling Center (CCMC). In particular, we identified the origin of CMEs using STEREO EUVI and/or SDO images. A flux-rope model fitting to the SECCHI A and B, SOHO/LASCO images was used to reconstruct the 3D structures of CMEs and determine their actual speeds. J-maps were obtained from COR-2/HI-1/HI-2 and simulations using ENLIL+cone model were conducted to study the formation and evolution of the CME-driven shocks in the inner heliosphere. We compared the simulation results with the observed height-time profiles of the shocks from white light and kilometric type II burst (Wind/WAVES) observations. The predicted shock arrival at Earth is compared with in-situ observations from ACE and Wind. We report the preliminary results of the study in this poster. @-------------------------------------------------------------------- Title: The Relation between Coronal Holes and CMEs during the Rise, Maximum and Declining Phases of the Solar Cycle 23 Authors: Mohamed, A. A.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Makela, P. A.; Xie, H.; Jung, H. Bibliographic Code: 2010AGUFMSH23B1852M Abstract We investigate the influence of coronal holes (CHs) on the propagation of CMEs considering both magnetic clouds (MCs) and non-magnetic clouds (non-MCs), during the three phases of the solar cycle 23. We consider events originating within a central meridian distance of 15&\#9675;. The influence of the CHs is computed as a fictitious force that depends on the CH area, the distance between the CH and the eruption region, and the magnetic field within the CH at the photospheric level. We find that the influence parameter is the smallest during the rise phase of the cycle and increases during the maximum and then in the declining phases. The largest influence parameter was observed to be for non-MCs in the Maximum phase F= 2.9 G. However, the average influence parameter is only about half of what was computed for driverless shocks F= 5.8 G. The CH effect on the non-MCs is found to be larger than that for MCs during maximum phase; this may suggest that non-MCs may also have flux rope structure which is hidden from observation due to the deflection by the nearby CHs as has been suggested in the case of driverless shocks (Gopalswamy et al., 2009, JGR). reference: Gopalswamy, N., p. Makela, H. Xie, S. Akiyama, and S. Yashiro, (2009), "CME Interaction with coronal holes and their interplanetary consequences" , J. Geophys. Res., 114,A00A22 doi:10.1029/2008JA013686. @-------------------------------------------------------------------- Title: Understanding Interplanetary Shock Dynamics in the Inner Heliosphere with New Observations and Modeling Techniques Authors: St Cyr, O. C.; Henning, C.; Xie, H.; Odstrcil, D.; Mays, L.; Cremades, H.; Iglesias, F.; Gopalswamy, N.; Kaiser, M. L. Bibliographic Code: 2010AGUFMSH23B1850S Abstract This is a status report of our work predicting interplanetary shock location and strength throughout the inner heliosphere. Coronal mass ejection (CME) shocks accelerate energetic particles, and CME sheaths and ejecta are the primary cause of severe geomagnetic storms. We have evaluated an empirical prediction technique against ENLIL model runs produced at the Community Coordinated Modelling Center (CCMC). The prediction method is a technique based on the kilometric wavelength interplanetary Type II radio emissions measured by Wind/WAVES and described by Cremades, et al., 2007 (hereafter called "kmTII" technique). For a subset of Earth-directed CMEs that were also observed by SOHO LASCO, we have produced multiple ENLIL+cone model predictions of the location of the shock and compared the predicted arrival of at Earth with both the actual arrival and the kmTII prediction. We will report the preliminary results of the comparison in this poster. @-------------------------------------------------------------------- Title: On the Occurrence of Energetic Storm Particle Events and Type II Radio Bursts in CME-driven Shocks Authors: Makela, P. A.; Gopalswamy, N.; Akiyama, S.; Xie, H.; Yashiro, S. Bibliographic Code: 2010AGUFMSH23B1847M Abstract We discuss correlations between energetic storm particle (ESP) events and type II radio emission associated with coronal mass ejection-driven shocks detected during 1996-2006. Shocks that could not be associated with any type II radio emission within metric-to-kilometric wavelength range were defined to be radio-quiet (RQ). All other shocks were defined to be radio-loud (RL). ESP events were identified from the 66 keV-50 MeV proton intensities measured by the Electron, Proton and Alpha Monitor (EPAM) instrument on the Advanced Composition Explorer (ACE) spacecraft and the Energetic and Relativistic Nuclei and Electron (ERNE) experiment on the Solar and Heliospheric Observatory (SOHO). Electron ESP events were identified in the 38-53 keV energy channel of EPAM. It is remarkable that a large fraction (32%) of RQ shocks produced a particle flux increase at energies above 1.8 MeV. On the other hand, only 52% of RL shocks produced ESP events. Electron ESP events were observed in 20% of RQ shocks and 39% of RL shocks. We also find that ESP events during RQ shocks are less intense than those associated with RL shocks. Among RQ shocks, those with an ESP event have slightly more eastern source longitudes (median longitude E07), whereas those without have more western longitudes (median longitude W03). This difference probably reflects the asymmetry in the relative size of ESP events between the eastern and western flanks of the shock. Our results indicate that type II emission is important for the occurrence of ESP events. RL shocks produce frequently ESP events, and the associated ESP events are also more intense than those observed during RQ shocks. The variability in the occurrence of ESP events and type II radio bursts is probably due to differences in the shock formation in the low corona and changes in the properties of the shocks as they propagate through interplanetary space, and the escape efficiency of accelerated particles from the shock front. @-------------------------------------------------------------------- Title: Statistical Study of Solar Activity Associated with SOHO UVCS Coronal Mass Ejections Authors: O'Neill, J. F.; St Cyr, O. C.; Mays, L.; Gopalswamy, N.; Raymond, J. C.; Ciaravella, A.; Yashiro, S.; Xie, H.; Giordano, S.; Quirk, C. Bibliographic Code: 2010AGUFMSH23B1838O Abstract Recently a preliminary catalogue of coronal mass ejections (CMEs) detected by the SOHO ultraviolet coronal spectrometer (UVCS) has been made available to the scientific community through the online LASCO CME catalogue (http://cdaw.gsfc.nasa.gov/). We have undertaken an initial study to identify solar activity associated with the UVCS CMEs with radio Type II events, and EUV and X-ray flares. Over 800 CMEs have been identified in UVCS data, and we have found associated activity for 185 events. In this poster we report the basic statistics as a function of time, longitude, latitude, CME speed, etc. @-------------------------------------------------------------------- Title: An Earth-Directed CME not Observed in LASCO Images Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S. Bibliographic Code: 2010AGUFMSH23A1835Y Abstract The COR1 coronagraphs on STEREO-A and -B observed an Earth-directed CME originating from N09W15 at 02:20 UT on 2010/07/09. The apparent CME speed is only 291 km/s, and the angular width is 60 degrees. The CME is somewhat slower than the average LASCO CME (average speed ~450 km/s) but not narrow. The CME was expected to be seen as a halo CME because of the geometry and large width. However, the CME could not be identified in the LASCO running difference movie because of the visibility of the white-light coronagraph. On the other hand, EUV images taken by SDO/AIA show a clear dimming to the northwest of the source region and a wave-like feature propagating to the east. Faint Earth-directed CMEs, seem to be better indicated by surface eruptive signatures such as dimming and EUV waves. We discuss how to estimate CME parameters using the EUV data alone. @-------------------------------------------------------------------- Title: Opportunities for Ionospheric Science as Part of the International Space Weather Initiative (ISWI) (Invited) Authors: Davila, J. M.; Gopalswamy, N.; Haubold, H. Bibliographic Code: 2010AGUFMSA43C..01D Abstract The International Heliophysical Year (IHY), which lasted for approximately two years and involved the effort of thousands of scientists from over 70 countries, ended in February 2009. The major objectives of the IHY included over 60 collaborative studies of universal physical processes in the solar system, the deployment of arrays of small instruments to observe heliophysical processes, a unique program of educational and public outreach, and the preservation of the history of the IGY. The International Space Weather Initiative (ISWI), an international effort fully supported by the United Nations, is designed to build on the momentum developed during the IHY to develop the capability to observe, understand, and predict space weather phenomena, and provide the opportunity for the deployment of new instrumentation in Africa and other regions. In this talk the basic elements of the ISWI will be discussed, and the opportunities for the deployment of new instrument will be discussed. @-------------------------------------------------------------------- Title: A Catalog of Halo Coronal Mass Ejections from SOHO Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Mäkelä, P.; Vourlidas, A.; Howard, R. A. Bibliographic Code: 2010SunGe...5....7G Abstract Coronal mass ejections (CMEs) that appear to surround the occulting disk of the observing coronagraph are known as halo CMEs. Halos constitute a subset of energetic CMEs that have important heliospheric consequences. Here we describe an on-line catalog that contains all the halo CMEs that were identified in the images obtained by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) since 1996. Until the end of 2007, some 396 halo CMEs were recorded. For each halo CME, we identify the solar source (heliographic coordinates), the soft X-ray flare importance, and the flare onset time. From the sky-plane speed measurements and the solar source information we obtain the space speed of CMEs using a cone model. In addition to the description of the catalog (http://cdaw.gsfc.nasa.gov/CME_list/HALO/halo.html), we summarize the statistical properties of the halo CMEs. We confirm that halo CMEs are twice faster than ordinary CMEs and are associated with major flares on the average. We also compared the annual rate of halo CMEs with that obtained by automatic detection methods and found that most of these methods have difficulty in identifying full halo CMEs. @-------------------------------------------------------------------- Title: Long-duration Low-frequency Type III Bursts and Solar Energetic Particle Events Authors: Gopalswamy, Nat; Mäkelä, Pertti Bibliographic Code: 2010ApJ...721L..62G Abstract We analyzed the coronal mass ejections (CMEs), flares, and type II radio bursts associated with a set of three complex, long-duration, low-frequency (<14 MHz) type III bursts from active region 10588 in 2004 April. The durations were measured at 1 and 14 MHz using data from Wind/WAVES and were well above the threshold value (>15 minutes) normally used to define these bursts. One of the three type III bursts was not associated with a type II burst, which also lacked a solar energetic particle (SEP) event at energies >25 MeV. The 1 MHz duration of the type III burst (28 minutes) for this event was near the median value of type III durations found for gradual SEP events and ground level enhancement events. Yet, there was no sign of an SEP event. On the other hand, the other two type III bursts from the same active region had similar duration but were accompanied by WAVES type II bursts; these bursts were also accompanied by SEP events detected by SOHO/ERNE. The CMEs for the three events had similar speeds, and the flares also had similar size and duration. This study suggests that the occurrence of a complex, long-duration, low-frequency type III burst is not a good indicator of an SEP event. @-------------------------------------------------------------------- Title: Expansion speed of Coronal Mass Ejections Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji Bibliographic Code: 2010EGUGA..12.5142M Abstract A large set of limb CMEs has been used to determine the accurate relationship between radial (V rad) and expansion (V exp) speeds of CMEs. It was demonstrated that this relation is exceptionally well described by the function f(w)= 1/2 (1 + cot (w)) representing a full cone model for the CME with a half width, w. We also demonstrated that this relation for the halo CMEs could be very simple V rad = V exp. @-------------------------------------------------------------------- Title: Large Geomagnetic Storms Associated with Limb Halo Coronal Mass Ejections Authors: Gopalswamy, Nat; Yashiro, Seiji; Xie, Hong; Akiyama, Sachiko; Mäkelä, Pertti Bibliographic Code: 2010aogs...21...71G, eprint = 0903.2776 Abstract Solar cycle 23 witnessed the observation of hundreds of halo coronal mass ejections (CMEs), thanks to the high dynamic range and extended field of view of the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. More than two thirds of halo CMEs originating on the front side of the Sun have been found to be geoeffective (Dst =< -50 nT). The delay time between the onset of halo CMEs and the peak of ensuing geomagnetic storms has been found to depend on the solar source location (Gopalswamy et al., 2007). In particular, limb halo CMEs (source longitude > 45deg) have a 20% shorter delay time on the average. It was suggested that the geomagnetic storms due to limb halos must be due to the sheath portion of the interplanetary CMEs (ICMEs) so that the shorter delay time can be accounted for. We confirm this suggestion by examining the sheath and ejecta portions of ICMEs from Wind and ACE data that correspond to the limb halos. Detailed examination showed that three pairs of limb halos were interacting events. Geomagnetic storms following five limb halos were actually produced by other disk halos. The storms followed by four isolated limb halos and the ones associated with interacting limb halos, were all due to the sheath portions of ICMEs. @-------------------------------------------------------------------- Title: Polar Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D. Bibliographic Code: 2010AAS...21640103G Abstract Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by 250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes. @-------------------------------------------------------------------- Title: Radioheliograph Observations of Metric Type II Bursts and the Kinematics of Coronal Mass Ejections Authors: Ramesh, R.; Kathiravan, C.; Kartha, Sreeja S.; Gopalswamy, N. Bibliographic Code: 2010ApJ...712..188R Abstract Assuming that metric type II radio bursts from the Sun are due to magnetohydrodynamic shocks driven by coronal mass ejections (CMEs), we estimate the average CME acceleration from its source region up to the position of the type II burst. The acceleration values are in the range ≈600-1240 m s^{-2}, which are consistent with values obtained using non-radio methods. We also find that (1) CMEs with comparatively larger acceleration in the low corona are associated with soft X-ray flares of higher energy; the typical acceleration of a CME associated with X1.0 class soft X-ray flare being ≈ 1020 m s^{-2}, and (2) CMEs with comparatively higher speed in the low corona slow down quickly at large distances from the Sun---the deceleration of a CME with a typical speed of 1000 km s^-1 being ≈ -15 m s^{-2} in the distance range of ≈3-32 R _sun. @-------------------------------------------------------------------- Title: Solar Sources of ``Driverless'' Interplanetary Shocks Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Akiyama, S.; Yashiro, S. Bibliographic Code: 2010AIPC.1216..452G Abstract We identify the solar sources of a large number of interplanetary (IP) shocks that do not have a discernible driver as observed by spacecraft along the Sun-Earth line. At the Sun, these ``driverless'' shocks are associated with fast and wide CMEs. Most of the CMEs were also driving shocks near the Sun, as evidenced by the association of IP type II radio bursts. Thus, all these shocks are driven by CMEs and they are not blast waves. Normally limb CMEs produce driverless shocks at 1 AU. But some disk-center CMEs also result in driverless shocks because of deflection by nearby coronal holes. We estimate the angular deflection to be in the range 20°-60°. We also compared the influence of nearby coronal holes on a set of CMEs that resulted in magnetic clouds. The influence is nearly three times larger in the case of driverless shocks, confirming the large deflection required. @-------------------------------------------------------------------- Title: The CME link to geomagnetic storms Authors: Gopalswamy, Nat Bibliographic Code: 2010IAUS..264..326G Abstract The coronal mass ejection (CME) link to geomagnetic storms stems from the southward component of the interplanetary magnetic field contained in the CME flux ropes and in the sheath between the flux rope and the CME-driven shock. A typical storm-causing CME is characterized by (i) high speed, (ii) large angular width (mostly halos and partial halos), and (iii) solar source location close to the central meridian. For CMEs originating at larger central meridian distances, the storms are mainly caused by the sheath field. Both the magnetic and energy contents of the storm-producing CMEs can be traced to the magnetic structure of active regions and the free energy stored in them. @-------------------------------------------------------------------- Title: Interplanetary Shocks Lacking Type II Radio Bursts Authors: Gopalswamy, N.; Xie, H.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J.-L. Bibliographic Code: 2010ApJ...710.1111G, eprint = 0912.4719 Abstract We report on the radio-emission characteristics of 222 interplanetary (IP) shocks detected by spacecraft at Sun-Earth L1 during solar cycle 23 (1996 to 2006, inclusive). A surprisingly large fraction of the IP shocks (~34%) was radio quiet (RQ; i.e., the shocks lacked type II radio bursts). We examined the properties of coronal mass ejections (CMEs) and soft X-ray flares associated with such RQ shocks and compared them with those of the radio-loud (RL) shocks. The CMEs associated with the RQ shocks were generally slow (average speed ~535 km s^-1) and only ~40% of the CMEs were halos. The corresponding numbers for CMEs associated with RL shocks were 1237 km s^-1 and 72%, respectively. Thus, the CME kinetic energy seems to be the deciding factor in the radio-emission properties of shocks. The lower kinetic energy of CMEs associated with RQ shocks is also suggested by the lower peak soft X-ray flux of the associated flares (C3.4 versus M4.7 for RL shocks). CMEs associated with RQ CMEs were generally accelerating within the coronagraph field of view (average acceleration ~+6.8 m s^-2), while those associated with RL shocks were decelerating (average acceleration ~-3.5 m s^-2). This suggests that many of the RQ shocks formed at large distances from the Sun, typically beyond 10 Rs, consistent with the absence of metric and decameter---hectometric (DH) type II radio bursts. A small fraction of RL shocks had type II radio emission solely in the kilometric (km) wavelength domain. Interestingly, the kinematics of the CMEs associated with the km type II bursts is similar to those of RQ shocks, except that the former are slightly more energetic. Comparison of the shock Mach numbers at 1 AU shows that the RQ shocks are mostly subcritical, suggesting that they were not efficient in accelerating electrons. The Mach number values also indicate that most of these are quasi-perpendicular shocks. The radio-quietness is predominant in the rise phase and decreases through the maximum and declining phases of solar cycle 23. About 18% of the IP shocks do not have discernible ejecta behind them. These shocks are due to CMEs moving at large angles from the Sun-Earth line and hence are not blast waves. The solar sources of the shock-driving CMEs follow the sunspot butterfly diagram, consistent with the higher-energy requirement for driving shocks. @-------------------------------------------------------------------- Title: Quasi-Periodic Oscillations in Lasco Coronal Mass Ejection Speeds Authors: Shanmugaraju, A.; Moon, Y.-J.; Cho, K.-S.; Bong, S. C.; Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Umapathy, S.; Vrsnak, B. Bibliographic Code: 2010ApJ...708..450S Abstract Quasi-periodic oscillations in the speed profile of coronal mass ejections (CMEs) in the radial distance range 2-30 solar radii are studied. We considered the height-time data of the 307 CMEs recorded by the Large Angle and Spectrometric Coronagraph (LASCO) during 2005 January-March. In order to study the speed-distance profile of the CMEs, we have used only 116 events for which there are at least 10 height-time measurements made in the LASCO field of view. The instantaneous CME speed is estimated using a pair of height-time data points, providing the speed-distance profile. We found quasi-periodic patterns in at least 15 speed-distance profiles, where the speed amplitudes are larger than the speed errors. For these events we have determined the speed amplitude and period of oscillations. The periods of quasi-periodic oscillations are found in the range 48-240 minutes, tending to increase with height. The oscillations have similar properties as those reported by Krall et al., who interpreted them in terms of the flux-rope model. The nature of forces responsible for the motion of CMEs and their oscillations are discussed. @-------------------------------------------------------------------- Title: Coronal Mass Ejections from Sunspot and Non-Sunspot Regions Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Mäkelä, P. Bibliographic Code: 2010mcia.conf..289G, eprint = 0903.1087 Abstract Coronal mass ejections (CMEs) originate from closed magnetic field regions on the Sun, which are active regions and quiescent filament regions. The energetic populations such as halo CMEs, CMEs associated with magnetic clouds, geoeffective CMEs, CMEs associated with solar energetic particles and interplanetary type II radio bursts, and shock-driving CMEs have been found to originate from sunspot regions. The CME and flare occurrence rates are found to be correlated with the sunspot number, but the correlations are significantly weaker during the maximum phase compared to the rise and declining phases. We suggest that the weaker correlation results from high-latitude CMEs from the polar crown filament regions that are not related to sunspots. @-------------------------------------------------------------------- Title: Large-Scale Solar Eruptions Authors: Gopalswamy, Natchimuthukonar Bibliographic Code: 2010hepr.book...53G Abstract This chapter provides an over view of coronal mass ejections (CMEs) and the associated flares including statistical properties, associated phenomena (solar energetic particles, interplanetary shocks, geomagnetic storms), and their heliospheric consequences. @-------------------------------------------------------------------- Title: Heliophysical Processes Authors: Gopalswamy, Natchimuthuk; Hasan, S.; Ambastha, Ashok Bibliographic Code: 2010hepr.book.....G Abstract @-------------------------------------------------------------------- Title: The International Space Weather Initiative Authors: Davila, Joseph; Gopalswamy, Nat Bibliographic Code: 2010cosp...38.4192D Abstract The International Space Weather Initiative (ISWI) is an international program of scientific collaboration to understand the external drivers of space weather. One of the major thrusts of the ISWI is to deploy arrays of small instruments such as magnetometers, radio antennas, GPS receivers, all-sky cameras, particle detectors, etc. around the world to provide global measurements of heliospheric phenomena. Scientists from approximately 70 countries now participate in the instrument operation, data collection, analysis, and publication of scientific results, working at the forefront of science research. The purpose of the ISWI is to continue the scientific study of universal processes in the solar system that affect space weather and the terrestrial environment, and to continue to coordinate the deployment and operation of new and existing instrument arrays aimed at understanding the impacts of Space Weather on Earth and the near-Earth environment. This project provides an excellent opportunity for potential instrument providers to engage collaborators from specific geographical locations, and to broaden the coverage of existing instrument arrays. By deploying instruments in strategically chosen locations new science and a more global view of heliophysical processes is obtained. These data will also provide new inputs for global ionospheric models in the future. @-------------------------------------------------------------------- Title: Investigating the relation between Coronal Holes and CMEs during the Rise, Maximum and Declining Phases of the Solar Cycle 23 Authors: Shahin, Amaal; Gopalswamy, Nat Bibliographic Code: 2010cosp...38.1918S Abstract In a study on the interaction between Coronal holes (CHs) and inter planetary coronal mass ejections (ICMEs) during the declining phase of solar cycle 23, Gopalswamy et al. [2009] showed that coronal holes (CHs) act as a magnetic wall that constrains the CME propagation. The CME trajectories are significantly affected when the eruptions occur in close proximity to CHs. Here, we investigate the influence of coronal holes on the propagation of CMEs through considering both ICMEs categories with and without flux rope structures during the rise and maximum phases of the solar cycle 23. We also, compare the results obtained with that of the declining phase and of the driverless shocks reported previously by Gopalswamy et al. [2009]. A list of ICMEs that are not classified as MCs has been developed from the Interplanetary (IP) shock list of the solar cycle 23 via selecting all disk center events (central meridian distance 15o ) that have been observed to be (MC s) which leaves us with another list includes the non MC events. The influence of the CHs is computed as a fictitious force that depends on the CH area, the distance between the CH and the eruption region, and the magnetic field within the CH at photospheric level. The open magnetic field distribution on the Sun is obtained for the MCs and non MCs solar events studied during the rise and maximum phases in addition to four magnetic cloud events were not included in Goplaswamy et al. [2009]. This open filed distribution is obtained through performing a potential field source surface extrapolation to the corona up to a heliocentric distance of 2.5 Rs. The Correlation Coefficient (CC) between the duration of the ICMEs and the resultant influence parameter F of the coronal holes is determined in the case of MCs and non MCs for rise, maximum and declining phases. The results show that the correlation coefficient in the case of magnetic cloud (MCs) events is very high at the rise phase ( 0.84) which confirms the correspondence between the non radial motion during the rise phase of the solar cycle and the higher magnetic field strength in the solar regions of the polar coronal holes existed in this phase. The difference between measured position angle (MPA) and the influence position angle (FPA) where F is pointing, () for the non MCs in the rise and maximum phases is found to be 34o and 35o; respectively which is consistent with that for driverless shocks given by Gopalswamy et al. [2009] (where 37o ). These results together with the average influence parameter value (F av 2.53 G) for the declining phase which is found to be the highest compared to the other two phases and also to the MCs average values suggest that the non MCs are resembling in their behavior the driverless shocks (which have been proven by Gopalswamy et al., 2009 to be deflected by the near by CH s away from the Sun-Earth line) and that the non MCs may have flux rope structure as the MCs do have but this structure is hidden from observation due to the deflection by CH s. This finding may have bearing on the idea that all CMEs may be flux ropes and the difference is only due to the viewing angle variation. @-------------------------------------------------------------------- Title: Prediction of the interplanetary Coronal Mass Ejection and it's associated shock by using neural network Authors: Mahrous, Ayman; Radi, Amr; Youssef, Mohamed; Faheem, Amin; Ahmed, Safinaz; Gopalswamy, Nat Bibliographic Code: 2010cosp...38.1905M Abstract We determined the effective parameter that can be used to predict the estimated arrival time for both Interplanetary Coronal Mass Ejection (ICME) and its associated shock (using the list of Richardson/Cane ICMEs in 1996-2007). Neural network model is used to predict ICME/shock and its arrival time. The set of CME-IP shock pairs obtain from Richardson/Cane ICMEs list is used to construct our neural model from (1996-2005). Concurrently, we determined the effective parameter that used CME-IP shock pairs from (2005-2007) to test our neural networks model. We found that the model succeeded to predict 97 @-------------------------------------------------------------------- Title: Estimation of coronal magnetic field using the type II radio burst associated with a fast CME Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Freeland, Samuel; Davila, Joseph; Howard, Russell; Bougeret, J.-L. Bibliographic Code: 2010cosp...38.1808G Abstract The 2008 March 25 coronal mass ejection (CME) was the second fastest among the 10 type II producing CMEs in the STEREO era. The CME was accompanied by a EUV wave and a shock discernible in the white-light data. The type II burst was observed in the metric and decameter-hectometer (DH) wavelength domains. The type II burst ended in the DH domain when the CME speed started declining at a heliocentric distance where the Alfven speed reached its peak value. Under the scenario that the type II burst was caused by a CME-driven shock, we see that the end of the type II burst corresponds to a significant weakening of the shock, making it subcritical. The standoff distance between the flux rope structure and the shock significantly increased at the time of the shock weakening. From the observed standoff distance, we estimated the upstream Alfvenic Mach number and hence the coronal magnetic field. The magnetic field derived (0.04 G) is consistent with typical quiet solar atmosphere at 7 solar radii. @-------------------------------------------------------------------- Title: Expansion Speed of Coronal Mass Ejections Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2009SoPh..260..401M Abstract A large set of limb coronal mass ejections (CMEs) are used to determine the accurate relationship between radial ( V _rad) and expansion ( V _exp) speeds of CMEs. It is demonstrated that this relation is exceptionally well described by the function f( w)=1/2(1+cot w), representing a full cone model for the CME with a half-width, w. We also demonstrate that for extremely fast CMEs ( V _exp>3000 km s^-1), it is better to use the approximation V _rad≈ V _LE. This implies that such CMEs expand spherically above the solar surface. @-------------------------------------------------------------------- Title: Relation between Magnetic Helicity and CME Speed in Source Active Regions Authors: Jung, H.; Gopalswamy, N.; Akiyama, S.; Yashiro, S. Bibliographic Code: 2009AGUFMSH41B1669J Abstract We report on a study linking the speed of coronal mass ejections (CMEs) to the magnetic helicity in the source active regions. The motivation comes from the fact that the CME speed may depend on the active region free magnetic energy, which in turn may be represented by the helicity, a proxy for the nonpotentiality. We selected a set of active regions from solar cycle 23, measured their helicity, and identified CMEs from the CME catalog (http://cdaw.gsfc.nasa.gov). Using EUV and magnetogram data from the Solar and Heliospheric Observatory (SOHO) mission, we measured the coronal helicity content before CME eruptions. We extrapolated the photospheric magnetic field to the corona to obtain the coronal helicity that fits a EUV image before each CME eruption. The CME speeds used here corresponds to the average speed within the SOHO coronagraphic field of view. We found that magnetic helicity is positively correlated with the speed of CME. We cross-checked the helicity values using the principle of magnetic helicity conservation connecting helicity obtained from the Local Correlation Tracking (LCT) method, the helicity of the associated magnetic clouds and the coronal helicity. @-------------------------------------------------------------------- Title: The 26 April 2008 CME; a Case Study Tracking a CME into the Heliosphere Authors: Webb, D. F.; Galvin, A. B.; Gopalswamy, N.; Howard, T. A.; Reinard, A. A.; Jackson, B.; Davis, C. Bibliographic Code: 2009AGUFMSH41A1640W Abstract With the current unique constellation of spacecraft, we are studying the origins of CMEs, their 3D structure and how they propagate through the heliosphere. Here we present the results of a case study of one well observed event that occurred during the Whole Heliosphere Interval (WHI), originating at the Sun on 26 April 2008. The event arose from a cluster of 3 active regions that evolved over several solar rotations centered on WHI. The CME was moderately fast with evidence of a shock and was associated with a coronal arcade, coronal dimming and an EUV wave. The April 26 CME originated from disk center for STEREO-B and apparently caused a small SEP event and shock and possible magnetic cloud at STEREO-B on April 29. A brief IP type II suggests that this event had the lowest starting frequency ever observed, which has implications for the medium through which the shock propagates. Possible ejecta was detected in situ at STEREO-B. The Fe charge states suggest that there was a CIR-type interface with some bidirectional electron streaming present. This is confirmed by SMEI 3D reconstructions of density indicating that the ICME interacted with a preexisting CIR. The ICME was also imaged by the SECCHI HI imagers; both the SMEI and HI data permit us to track the dense material from the Sun past 1 AU. @-------------------------------------------------------------------- Title: Interplanetary Proton and Electron Enhancements Associated with Radio-loud and Radio-quiet CME-driven Shocks Authors: Makela, P. A.; Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro, S. Bibliographic Code: 2009AGUFMSH33A1477M Abstract We present the results on electron and proton acceleration in association with radio-quiet (RQ) and radio-loud (RL) shocks driven by coronal mass ejections (CMEs) during 1996-2006. The CME-driven shocks are classified into RL or RQ shocks based on the presence or the lack of type II radio bursts in the metric and decameter-hectometric wavelength range. We studied proton flux enhancements at L1 in the 66 keV - 50 MeV energy range observed by the ACE/EPAM and SOHO/ERNE instruments. Electron flux enhancements were studied in the 38-53~keV energy channel of EPAM. In general, the RL shocks are more likely to be associated with an energetic storm particle (ESP) event than RQ shocks. Approximately one third of RQ shocks and slightly over a half of RL shocks produced an ESP event at energies above 1.8 MeV. In overall both RQ and RL electron ESP events are rarer, but they follow a similar pattern to the proton observations, i.e. ESP events are observed in approximately one fifth versus two fifths of shocks, respectively. We also studied correlations of ESP event size with CME and shock properties. As expected, the ESP events associated with the RQ shocks are less intense than those with RL shocks. In addition, particle acceleration in RQ shocks occurs predominately in quasi-perpendicular shocks. There is a modest positive correlation between ESP event size and the CME and shock speed and the Mach number. Again, the correlations are stronger for the RL shocks. It appears that shocks can accelerate particles, although less efficiently, even when they do not produce observable type II radio bursts. The variation between the presence of type IIs and ESP events is probably connected to variations in the coronal conditions of shock formation and to the consequent evolution of the shock as it travels through diverse coronal and interplanetary plasmas. @-------------------------------------------------------------------- Title: The relation between solar active region location and the lowest frequency of type III emission Authors: Kuroda, N.; Gopalswamy, N. Bibliographic Code: 2009AGUFMSH23A1522K Abstract We have investigated the relation between the lowest frequencies of type III bursts and the locations of source active regions from which the causal electron beams originate. We chose several active regions that produced coronal mass ejections (CMEs) and flares during their disk passage. The type III bursts considered in this study originated from these eruptions. The CMEs were detected by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric coronagraph (LASCO). The type III bursts were observed by the Radio and Plasma Wave Experiment (WAVES) on board Wind. By tracking the type III bursts into the spectral range covered by the Thermal Noise Receiver (TNR) on board Wind, we were able to measure the lowest frequency reached by 104 type III bursts from 17 active regions. In addition, we were able to measure the frequency separation between the type III bursts and the local plasma frequency at the Wind spacecraft as measured by TNR. Because the type III bursts were produced when the source active regions were at various central meridian distances, we could study the lowest frequency at which the type III bursts occurred as a function of the source longitude. We found that the type III emission occurs at frequencies close to the local plasma frequency at the spacecraft when the source active regions are at the disk center or in the western hemisphere. Type III bursts from active regions close to the east limb of the Sun have a higher cutoff frequency. This can be explained by the fact that type III bursts from eastern active regions cannot propagate to the Wind spacecraft because of the intervening denser plasma regions Further investigation is needed to understand the large scatter in the data points, especially those that do not follow the expected tendency: a closer examination would reveal the condition of interplanetary medium and the state of solar wind at the time of these irregular points. @-------------------------------------------------------------------- Title: The subdued solar cycle 23/24 minimum revealed by microwave butterfly diagram Authors: Gopalswamy, N.; Yashiro, S.; Makela, P. A.; Shibasaki, K. Bibliographic Code: 2009AGUFMSH13C..02G Abstract The 17 GHz microwave brightness temperature in coronal holes is typically enhanced by 500 to 2000 K with respect to the quiet Sun. This is considered to be a property of the upper chromosphere, where the plasma temperature is ~10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama Radioheliograph and compared it with the magnetic butterfly diagram. We found a good correlation between the microwave brightness enhancement and the polar field strength. We also performed a rotation-by-rotation comparison between the two data sets to obtain the correlation between the magnetic field strength and the microwave brightness temperature. The microwave butterfly diagram covers part of cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by ~250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen e.g., in the SOHO/MDI magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes. @-------------------------------------------------------------------- Title: Recent STEREO Observations of Coronal Mass Ejections Authors: St Cyr, O. C.; Xie, H.; Mays, M. L.; Davila, J. M.; Gilbert, H. R.; Jones, S. I.; Pesnell, W. D.; Gopalswamy, N.; Gurman, J. B.; Yashiro, S.; Wuelser, J.; Howard, R. A.; Thompson, B. J.; Thompson, W. T. Bibliographic Code: 2009AGUFMSH11A1491S Abstract Over 400 CMEs have been observed by STEREO SECCHI COR1 during the mission's three year duration (2006-2009). Many of the solar activity indicators have been at minimal values over this period, and the Carrington rotation-averaged CME rate has been comparable to that measured during the minima between Cycle 21-22 (SMM C/P) and Cycle 22-23 (SOHO LASCO). That rate is about 0.5 CMEs/day. During the current solar minimum (leading to Cycle 24), there have been entire Carrington rotations where no sunspots were detected and the daily values of the 2800 MHz solar flux remained below 70 sfu. CMEs continued to be detected during these exceptionally quiet periods, indicating that active regions are not necessary to the generation of at least a portion of the CME population. In the past, researchers were limited to a single view of the Sun and could conclude that activity on the unseen portion of the disk might be associated with CMEs. But as the STEREO mission has progressed we have been able to observe an increasing fraction of the Sun's corona with STEREO SECCHI EUVI and were able to eliminate this possibility. Here we report on the nature of CMEs detected during these exceptionally-quiet periods, and we speculate on how the corona remains dynamic during such conditions. @-------------------------------------------------------------------- Title: Relation Between Type II Bursts and CMEs Inferred from STEREO Observations Authors: Gopalswamy, N.; Thompson, W. T.; Davila, J. M.; Kaiser, M. L.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Bougeret, J.-L.; Howard, R. A. Bibliographic Code: 2009SoPh..259..227G Abstract The inner coronagraph (COR1) of the Solar Terrestrial Relations Observatory (STEREO) mission has made it possible to observe CMEs in the spatial domain overlapping with that of the metric type II radio bursts. The type II bursts were associated with generally weak flares (mostly B and C class soft X-ray flares), but the CMEs were quite energetic. Using CME data for a set of type II bursts during the declining phase of solar cycle 23, we determine the CME height when the type II bursts start, thus giving an estimate of the heliocentric distance at which CME-driven shocks form. This distance has been determined to be ˜1.5 R _s (solar radii), which coincides with the distance at which the Alfvén speed profile has a minimum value. We also use type II radio observations from STEREO/WAVES and Wind/WAVES observations to show that CMEs with moderate speed drive either weak shocks or no shock at all when they attain a height where the Alfvén speed peaks (˜3 R _s - 4 R _s). Thus the shocks seem to be most efficient in accelerating electrons in the heliocentric distance range of 1.5 R _s to 4 R _s. By combining the radial variation of the CME speed in the inner corona (CME speed increase) and interplanetary medium (speed decrease) we were able to correctly account for the deviations from the universal drift-rate spectrum of type II bursts, thus confirming the close physical connection between type II bursts and CMEs. The average height (˜1.5 R _s) of STEREO CMEs at the time of type II bursts is smaller than that (2.2 R _s) obtained for SOHO ( Solar and Heliospheric Observatory) CMEs. We suggest that this may indicate, at least partly, the density reduction in the corona between the maximum and declining phases, so a given plasma level occurs closer to the Sun in the latter phase. In two cases, there was a diffuse shock-like feature ahead of the main body of the CME, indicating a standoff distance of 1 R _s - 2 R _s by the time the CME left the LASCO field of view. @-------------------------------------------------------------------- Title: On the Origin, 3D Structure and Dynamic Evolution of CMEs Near Solar Minimum Authors: Xie, H.; St. Cyr, O. C.; Gopalswamy, N.; Yashiro, S.; Krall, J.; Kramar, M.; Davila, J. Bibliographic Code: 2009SoPh..259..143X Abstract We have conducted a statistical study 27 coronal mass ejections (CMEs) from January 2007 - June 2008, using the stereoscopic views of STEREO SECCHI A and B combined with SOHO LASCO observations. A flux-rope model, in conjunction with 3D triangulations, has been used to reconstruct the 3D structures and determine the actual speeds of CMEs. The origin and the dynamic evolution of the CMEs are investigated using COR1, COR2 and EUVI images. We have identified four types of solar surface activities associated with CMEs: i) total eruptive prominence (totEP), ii) partially eruptive prominence (PEP), iii) X-ray flare, and iv) X-type magnetic structure (X-line). Among the 27 CMEs, 18.5% (5 of 27) are associated with totEPs, 29.6% (8 of 27) are associated with PEPs, 26% (7 of 27) are flare related, and 26% (7 of 27) are associated with X-line structures, and 43% (3 of 7) are associated with both X-line structures and PEPs. Three (11%) could not be associated with any detectable activity. The mean actual speeds for totEP-CMEs, PEP-CMEs, flare-CMEs, and X-line-CMEs are 404 km s^-1,247 km s^-1,909 km s^-1, and 276 km s^-1, respectively; the average mean values of edge-on and broadside widths for the 27 CMEs are 52 and 85 degrees, respectively. We found that slow CMEs ( V<=400 km s^-1) tend to deflect towards and propagate along the streamer belts due to the deflections by the strong polar magnetic fields of corona holes, while some faster CMEs show opposite deflections away from the streamer belts. @-------------------------------------------------------------------- Title: Erratum to ``Solar sources and geospace consequences of interplanetary magnetic clouds observed during solar cycle 23---Paper 1'' [J. Atmos. Sol.-Terr. Phys. 70(2-4) (2008) 245-253] Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P. Bibliographic Code: 2009JASTP..71.1005G Abstract @-------------------------------------------------------------------- Title: Properties of Solar Active Regions and Their Relationship with Solar Eruption: a Statistical Study Authors: Liu, Yang; Akiyama, S.; Gopalswamy, N.; Mason, J.; Nitta, N.; Tylka, A.; Yashiro, S.; Yurchyshyn, V. Bibliographic Code: 2009SPD....40.0920L Abstract Using magnetograms taken by SOHO/MDI, we have calculated some parameters for solar active regions, and explored possible relationships between them and solar eruptions. The parameters of active regions we studied are magnetic flux, net flux, potential field energy, orientation and separation. We also estimated decay index of magnetic field overlying the neutral line, and the configuration of ambient field under which the active region sits. The data used were taken from 1996 to 2005. With these results as a reference, we studied the active regions that produced the large solar energetic particle (SEP) events, or produced ground level enhancement (GLE) events. Comparison is also made between the active regions that produced full eruption and confine eruption (based on an event list published by Yashiro et al 2005, JGR, 11012S05Y). We present our results here, together with a discussion. @-------------------------------------------------------------------- Title: Halo coronal mass ejections and geomagnetic storms Authors: Gopalswamy, N. Bibliographic Code: 2009EP&S...61..595G Abstract In this letter, I show that the discrepancies in the geoeffectiveness of halo coronal mass ejections (CMEs) reported in the literature arise due to the varied definitions of halo CMEs used by different authors. In particular, I show that the low geoeffectiveness rate is a direct consequence of including partial halo CMEs. The geoeffectiveness of partial halo CMEs is lower because they are of low speed and likely to make a glancing impact on Earth. @-------------------------------------------------------------------- Title: The SOHO/LASCO CME Catalog Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Stenborg, G.; Vourlidas, A.; Freeland, S.; Howard, R. Bibliographic Code: 2009EM&P..104..295G Abstract Coronal mass ejections (CMEs) are routinely identified in the images of the solar corona obtained by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) since 1996. The identified CMEs are measured and their basic attributes are cataloged in a data base known as the SOHO/LASCO CME Catalog. The Catalog also contains digital data, movies, and plots for each CME, so detailed scientific investigations can be performed on CMEs and the related phenomena such as flares, radio bursts, solar energetic particle events, and geomagnetic storms. This paper provides a brief description of the Catalog and summarizes the statistical properties of CMEs obtained using the Catalog. Data products relevant to space weather research and some CME issues that can be addressed using the Catalog are discussed. The URL of the Catalog is: http://cdaw.gsfc.nasa.gov/CME_list . @-------------------------------------------------------------------- Title: Preface to the Proceedings of the European General Assembly and the United Nations Workshop Authors: Gopalswamy, N.; Eichhorn, G.; Sakurai, T.; Haubold, H. J. Bibliographic Code: 2009EM&P..104..139G Abstract @-------------------------------------------------------------------- Title: CME interactions with coronal holes and their interplanetary consequences Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Akiyama, S.; Yashiro, S. Bibliographic Code: 2009JGRA..11400A22G Abstract A significant number of interplanetary shocks (~17%) during cycle 23 were not followed by drivers. The number of such ``driverless'' shocks steadily increased with the solar cycle with 15%, 33%, and 52% occurring in the rise, maximum, and declining phase of the solar cycle. The solar sources of 15% of the driverless shocks were very close the central meridian of the Sun (within ~15°), which is quite unexpected. More interestingly, all the driverless shocks with their solar sources near the solar disk center occurred during the declining phase of solar cycle 23. When we investigated the coronal environment of the source regions of driverless shocks, we found that in each case there was at least one coronal hole nearby, suggesting that the coronal holes might have deflected the associated coronal mass ejections (CMEs) away from the Sun-Earth line. The presence of abundant low-latitude coronal holes during the declining phase further explains why CMEs originating close to the disk center mimic the limb CMEs, which normally lead to driverless shocks due to purely geometrical reasons. We also examined the solar source regions of shocks with drivers. For these, the coronal holes were located such that they either had no influence on the CME trajectories, or they deflected the CMEs toward the Sun-Earth line. We also obtained the open magnetic field distribution on the Sun by performing a potential field source surface extrapolation to the corona. It was found that the CMEs generally move away from the open magnetic field regions. The CME-coronal hole interaction must be widespread in the declining phase and may have a significant impact on the geoeffectiveness of CMEs. @-------------------------------------------------------------------- Title: Introduction to special section on Large Geomagnetic Storms Authors: Gopalswamy, N. Bibliographic Code: 2009JGRA..11400A00G Abstract Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm-causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst <= -100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section. @-------------------------------------------------------------------- Title: Modeling and prediction of fast CME/shocks associated with type II bursts Authors: Xie, H.; Gopalswamy, N.; Cyr, O. C. St. Bibliographic Code: 2009IAUS..257..489X Abstract A numerical simulation with ENLIL+Cone model was carried out to study the propagation of the shock driven by the 2005 May 13 CME. We then conducted a statistical analysis on a subset of similar events, where a decameter-hectometric (DH) type II radio burst and a counterpart kilometric type II have been observed to be associated with each CME (DHkm CME). The simulation results show that fast CME-driven shocks experienced a rapid deceleration as they propagated through the corona and then kept a nearly constant speed traveling out into the heliosphere. Two improved methods are proposed to predict the fast CME-driven shock arrival time, which give the prediction errors of 3.43 and 6.83 hrs, respectively. @-------------------------------------------------------------------- Title: SEPs and CMEs during cycle 23 Authors: Mäkelä, Pertti; Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Xie, Hong; Valtonen, Eino Bibliographic Code: 2009IAUS..257..475M Abstract We present a study of solar energetic particles (SEPs) in association with coronal mass ejections (CMEs) and type II radio bursts. The particle and CME observations cover the years 1996-2007. We find that heavy-ion events in association with type II bursts and proton events are produced in more western and most energetic CMEs. In addition, the source distribution of type II associated proton events with heavy ions reminds the source distribution expected for events with flare particles. Therefore, the estimation of relative contributions by flares and shocks in SEP events and separation of suggested different particle acceleration models is complicated. @-------------------------------------------------------------------- Title: Major solar flares without coronal mass ejections Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S. Bibliographic Code: 2009IAUS..257..283G Abstract We examine the source properties of X-class soft X-ray flares that were not associated with coronal mass ejections (CMEs). All the flares were associated with intense microwave bursts implying the production of high energy electrons. However, most (85%) of the flares were not associated with metric type III bursts, even though open field lines existed in all but two of the active regions. The X-class flares seem to be truly confined because there was no material ejection (thermal or nonthermal) away from the flaring region into space. @-------------------------------------------------------------------- Title: Statistical relationship between solar flares and coronal mass ejections Authors: Yashiro, Seiji; Gopalswamy, Nat Bibliographic Code: 2009IAUS..257..233Y Abstract We report on the statistical relationships between solar flares and coronal mass ejections (CMEs) observed during 1996-2007 inclusively. We used soft X-ray flares observed by the Geostationary Operational Environmental Satellite (GOES) and CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. Main results are (1) the CME association rate increases with flare's peak flux, fluence, and duration, (2) the difference between flare and CME onsets shows a Gaussian distribution with the standard deviation sigma = 17 min (sigma = 15 min) for the first (second) order extrapolated CME onset, (3) the most frequent flare site is under the center of the CME span, not near one leg (outer edge) of the CMEs, (4) a good correlation was found between the flare fluence versus the CME kinetic energy. Implications for flare-CME models are discussed. @-------------------------------------------------------------------- Title: Universal processes in heliophysics Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J. Bibliographic Code: 2009IAUS..257...11D Abstract The structure of the Universe is determined primarily by the interplay of gravity which is dominant in condensed objects, and the magnetic force which is dominant in the rarefied medium between condensed objects. Each of these forces orders the matter into a set of characteristic structures each with the ability to store and release energy in response to changes in the external environment. For the most part, the storage and release of energy proceeds through a number of Universal Processes. The coordinated study of these processes in different settings provides a deeper understanding of the underlying physics governing Universal Processes in astrophysics. @-------------------------------------------------------------------- Title: Universal Heliophysical Processes Authors: Gopalswamy, N.; Webb, D. F. Bibliographic Code: 2009IAUS..257.....G Abstract @-------------------------------------------------------------------- Title: Evolution of the anemone AR NOAA 10798 and the related geo-effective flares and CMEs Authors: Asai, Ayumi; Shibata, Kazunari; Ishii, Takako T.; Oka, Mitsuo; Kataoka, Ryuho; Fujiki, Ken'ichi; Gopalswamy, Nat Bibliographic Code: 2009JGRA..11400A21A, eprint = 0812.2063 Abstract We present a detailed examination of the features of the active region (AR) NOAA 10798. This AR generated coronal mass ejections (CMEs) that caused a large geomagnetic storm on 24 August 2005 with the minimum Dst index of -216 nT. We examined the evolution of the AR and the features on/near the solar surface and in the interplanetary space. The AR emerged in the middle of a small coronal hole, and formed a sea anemone like configuration. Halpha filaments were formed in the AR, which have southward axial field. Three M class flares were generated, and the first two that occurred on 22 August 2005 were followed by Halo-type CMEs. The speeds of the CMEs were fast, and recorded about 1200 and 2400 km s^-1, respectively. The second CME was especially fast, and caught up and interacted with the first (slower) CME during their travelings toward Earth. These acted synergically to generate an interplanetary disturbance with strong southward magnetic field of about -50 nT, which was followed by the large geomagnetic storm. @-------------------------------------------------------------------- Title: EUV Wave Reflection from a Coronal Hole Authors: Gopalswamy, N.; Yashiro, S.; Temmer, M.; Davila, J.; Thompson, W. T.; Jones, S.; McAteer, R. T. J.; Wuelser, J.-P.; Freeland, S.; Howard, R. A. Bibliographic Code: 2009ApJ...691L.123G Abstract We report on the detection of EUV wave reflection from a coronal hole, as observed by the Solar Terrestrial Relations Observatory mission. The EUV wave was associated with a coronal mass ejection (CME) erupting near the disk center. It was possible to measure the kinematics of the reflected waves for the first time. The reflected waves were generally slower than the direct wave. One of the important implications of the wave reflection is that the EUV transients are truly a wave phenomenon. The EUV wave reflection has implications for CME propagation, especially during the declining phase of the solar cycle when there are many low-latitude coronal holes. @-------------------------------------------------------------------- Title: Putting the "I" in IHY: The United Nations Report for the International Heliophysical Year 2007 Authors: Thompson, Barbara J.; Gopalswamy, Natchimuthuk; Davila, Joseph M.; Haubold, Hans J. Bibliographic Code: 2009piih.rept.....T Abstract @-------------------------------------------------------------------- Title: Commission 49: Interplanetary Plasma and Heliosphere Authors: Bougeret, Jean-Louis; von Steiger, Rudolf; Webb, David F.; Ananthakrishnan, Subramanian; Cane, Hilary V.; Gopalswamy, Natchimuthuk; Kahler, Stephen W.; Lallement, Rosine; Sanahuja, Blai; Shibata, Kazunari; Vandas, Marek; Verheest, Frank Bibliographic Code: 2009IAUTA..27..124B Abstract Commission 49 covers research on the solar wind, shocks and particle acceleration, both transient and steady-state, e.g., corotating, structures within the heliosphere, and the termination shock and boundary of the heliosphere. @-------------------------------------------------------------------- Title: Commission 10: Solar Activity Authors: Klimchuk, James A.; van Driel-Gesztelyi, Lidia; Schrijver, Carolus J.; Melrose, Donald B.; Fletcher, Lyndsay; Gopalswamy, Natchimuthuk; Harrison, Richard A.; Mandrini, Cristina H.; Peter, Hardi; Tsuneta, Saku; Vrsnak, Bojan; Wang, Jing-Xiu Bibliographic Code: 2009IAUTA..27...79K Abstract Commission 10 deals with solar activity in all of its forms, ranging from the smallest nanoflares to the largest coronal mass ejections. This report reviews scientific progress over the roughly two-year period ending in the middle of 2008. This has been an exciting time in solar physics, highlighted by the launches of the Hinode and STEREO missions late in 2006. The report is reasonably comprehensive, though it is far from exhaustive. Limited space prevents the inclusion of many significant results. The report is divided into the following sections: Photosphere and chromosphere; Transition region; Corona and coronal heating; Coronal jets; flares; Coronal mass ejection initiation; Global coronal waves and shocks; Coronal dimming; The link between low coronal CME signatures and magnetic clouds; Coronal mass ejections in the heliosphere; and Coronal mass ejections and space weather. Primary authorship is indicated at the beginning of each section. @-------------------------------------------------------------------- Title: Coronal mass ejections and space weather Authors: Gopalswamy, N. Bibliographic Code: 2009cwse.conf...77G Abstract Solar energetic particles (SEPs) and geomagnetic storms are the two primary space weather consequences of coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs). I summarize the observed properties of CMEs and ICMEs, paying particular attention to those properties that determine the ability of CMEs in causing space weather. Then I provide observational details of two the central issues: (i) for producing geomagnetic storms, the solar source location and kinematics along with the magnetic field structure and intensity are important, and (ii) for SEPs, the shock-driving ability of CMEs, the Alfven speed in the ambient medium, and the connectivity to Earth are crucial parameters. @-------------------------------------------------------------------- Title: The Expansion and Radial Speeds of Coronal Mass Ejections Authors: Gopalswamy, N.; Dal Lago, A.; Yashiro, S.; Akiyama, S. Bibliographic Code: 2009CEAB...33..115G Abstract We show the relation between radial (V_{rad}) and expansion (V_{exp}) speeds of coronal mass ejections (CMEs) depends on the CME width. As CME width increases, {V_{rad}/V_{exp}} decreases from a value >1 to <1. For widths approaching 180°, the ratio approaches 0 if the cone has a flat base, while it approaches 0.5 if the base has a bulge (ice cream cone). The speed difference between the limb and disk halos and the spherical expansion of super fast CMEs can be explained by the width dependence. @-------------------------------------------------------------------- Title: Solar connections of geoeffective magnetic structures Authors: Gopalswamy, N. Bibliographic Code: 2008JASTP..70.2078G Abstract Coronal mass ejections (CMEs) and high-speed solar wind streams (HSS) are two solar phenomena that produce large-scale structures in the interplanetary (IP) medium. CMEs evolve into interplanetary CMEs (ICMEs) and the HSS result in corotating interaction regions (CIRs) when they interact with preceding slow solar wind. This paper summarizes the properties of these structures and describes their geoeffectiveness. The primary focus is on the intense storms of solar cycle 23 because this is the first solar cycle during which simultaneous, extensive, and uniform data on solar, IP, and geospace phenomena exist. After presenting illustrative examples of coronal holes and CMEs, I discuss the internal structure of ICMEs, in particular the magnetic clouds (MCs). I then discuss how the magnetic field and speed correlate in the sheath and cloud portions of ICMEs. CME speed measured near the Sun also has significant correlations with the speed and magnetic field strengths measured at 1 AU. The dependence of storm intensity on MC, sheath, and CME properties is discussed pointing to the close connection between solar and IP phenomena. I compare the delay time between MC arrival at 1 AU and the peak time of storms for the cloud and sheath portions and show that the internal structure of MCs leads to the variations in the observed delay times. Finally, we examine the variation of solar-source latitudes of IP structures as a function of the solar cycle and find that they have to be very close to the disk center. @-------------------------------------------------------------------- Title: On the Characteristics of Shocks driven by limb CMEs Authors: Xie, H.; Gopalswamy, N.; Stcyr, C. Bibliographic Code: 2008AGUFMSH23B1650X Abstract We investigate the characteristics of bow shocks driven by limb CMEs near the Sun, including speed, width, compression ratio, and the relationshipof the standoff distance with CME size (the radius of curvature of a CME) and shock Mach number. We choose a subset of limb CMEs with distinct association of the decameter- hectometric (DH) type II burst, which is a good evidence of the existence CME-driven shock. The DH spectral domain corresponds to plasma frequencies within the field view of the SOHO/LASCO coronagraphs. Choosing limb events has several advantages: 1) there is no projection effects for CME speed measurements, 2) it is easier to determine the width of a CME and the front bow shock, 3) there is high confidence level for the plasma density determination from the white-light CME brightness. By studying the shock stand off distance and compression ratio, we obtain the shock Mach number and the Alfven speed profile in the corona. @-------------------------------------------------------------------- Title: Difference Between Magnetic Clouds and Non-cloud Ejecta in the Interplanetary Medium Authors: Gopalswamy, N. Bibliographic Code: 2008AGUFMSH22A..01G Abstract Solar cycle 23 has witnessed the accumulation of data on an unprecedented number of coronal mass ejections (CMEs) at the Sun and in the interplanetary (IP) medium, thanks to the large array of spaceborne observatories such as SOHO, Wind, and ACE. These observations have helped us make significant progress on the structure and evolution of CMEs in the inner heliosphere. One important question is whether the magnetic cloud (MC) and non-cloud ejecta have any difference in their solar origin. The ubiquitous nature of post-eruption arcades suggests that there should not be any difference. However, CMEs associated with MCs all originate from very close to the solar disk center (both in latitude and longitude). To zeroth order, the non-cloud ejecta seem to originate at larger central meridian distances (CMDs). In the extreme case of shocks without discernible ejecta, the corresponding CMEs have their solar sources near the limb. These observations suggest that whether one observes a flux rope (MC) or not depends mainly on the location of the observer with respect to the Sun-Earth line. Observations from solar cycle 23 indicate that there are significant deviations from the zeroth order picture, especially for non-cloud ejecta and the "driverless shocks": their solar sources near the disk center. The question is whether these ejecta do not have flux-rope structure by birth or they somehow got deflected away from the Sun-Earth line by other large- scale structures in the IP medium. The latter seems to be true for at least a subset of events, which seems to be affected by coronal holes located between the eruption center and the Sun-Earth line. This needs to be checked for all the events that deviate from the zeroth order picture. Charge-state signatures of MCs and non-cloud ejecta also support such a picture: the solar sources of IP CMEs with high charge states seem to originate close to the disk center, similar to the MC-associated CMEs. Another piece of evidence comes from the high correspondence between halo CMEs and MCs, both of which are highly geoeffective. Halo CMEs originating at larger CMDs produce geomagnetic storms via their sheath fields, again pointing to the importance of geometry. Contrary to importance of internal structure of CMEs for geoeffectiveness, the production of gradual solar energetic particle (SEP) should not depend on the internal structure of CMEs if the particles are accelerated by CME-driven shocks. In fact, there is a significant difference in the source distribution of SEP-producing CMEs (western sources) and MC CMEs (close to disk center). This paper illustrates these results using coronal and IP data. @-------------------------------------------------------------------- Title: Conservation of open solar magnetic flux and the floor in the heliospheric magnetic field Authors: Owens, M. J.; Crooker, N. U.; Schwadron, N. A.; Horbury, T. S.; Yashiro, S.; Xie, H.; St. Cyr, O. C.; Gopalswamy, N. Bibliographic Code: 2008AGUFMSH12A..05O Abstract The near-Earth heliospheric magnetic field intensity, |B|, exhibits a strong solar cycle variation, but returns to the same "floor" value each solar minimum. The current minimum, however, has seen |B| drop below previous minima, bringing in to question the existence of a floor, or at the very least requiring a re-assessment of its value. In this study we assume heliospheric flux consists of a constant open flux component and a time-varying contribution from CMEs. In this scenario, the true floor is |B| with zero CME contribution. Using observed CME rates over the solar cycle, we estimate the "no-CME" |B| floor at ~4.2± 0.5 nT, lower than previous floor estimates and below |B| observed this solar minimum. We speculate that the drop in |B| observed this minimum may be due to a persistently lower CME rate than the previous minimum, though there are large uncertainties in the supporting observational data. @-------------------------------------------------------------------- Title: Relation between Coronal Mass Ejection, Type II Radio Burst, and EUV Wave during the 2008 March 25 STEREO Event Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Freeland, S.; Thompson, W. T.; Davila, J. M.; Howard, R. A.; Kaiser, M. L.; Bougeret, J.- Bibliographic Code: 2008AGUFMSH12A..02G Abstract STEREO and SOHO observations of the March 25, 2008 coronal mass ejection (CME) provide an excellent opportunity to study its early evolution from multiple view points. The CME was fast (980 km/s) and wide (112 degrees) from the east limb of the Sun as viewed by SOHO. The STEREO spacecraft were separated by about 50 degrees, so the CME was a disk event for the STEREO-behind spacecraft and a behind-the-limb event for STEREO-ahead. The CME was associated with a well defined EUV wave as observed by the STEREO/EUVI instrument, a metric type II burst, and a multi-component type II burst observed by the STEREO/WAVES and Wind/WAVES instruments. One of the important aspect of this CME is that it was well observed by STEREO/SECCHI inner coronagraph (COR1) when the metric type II burst was in progress, so we are able to obtain the shock height with respect t the CME. This enabled us to infer the connection the coronal shock driven by the CME (inferred from type II burst) and the EUV wave. It appears that the EUV wave steepened into a shock and produced the type II burst. The multiple components of the type II burst were not harmonically related, so we examined the circumstances of the eruption. CME was ejected in the region between two streamers, so the CME-driven shock is likely to simultaneously encounter high and low- density regions of the corona, thus producing type II bursts at widely separated frequencies. This paper summarizes these observations and explains how the CME, type II radio burst, and EUV waves all fit together. @-------------------------------------------------------------------- Title: Outreach activities during the 2006 total solar eclipse sponsored by the International Heliophysical Year Authors: Rabello Soares, M. C.; Rabiu, A. B.; Gopalswamy, N.; Thompson, B. J.; Davila, J. M.; Sobrinho, A. A. Bibliographic Code: 2008AdSpR..42.1792R Abstract The International Heliophysical Year (IHY) is an international program of scientific research to advance our understanding of the physical processes that govern the Sun, Earth and heliosphere. It has a strong educational component, linking research and education. Here, we describe the outreach activities during the 2006 total solar eclipse sponsored by IHY. @-------------------------------------------------------------------- Title: Comment on ``Prediction of the 1-AU arrival times of CME-associated interplanetary shocks: Evaluation of an empirical interplanetary shock propagation model'' by K.-H. Kim et al. Authors: Gopalswamy, N.; Xie, H. Bibliographic Code: 2008JGRA..11310105G Abstract Abstract Available from http://www.agu.org @-------------------------------------------------------------------- Title: Conservation of open solar magnetic flux and the floor in the heliospheric magnetic field Authors: Owens, M. J.; Crooker, N. U.; Schwadron, N. A.; Horbury, T. S.; Yashiro, S.; Xie, H.; St. Cyr, O. C.; Gopalswamy, N. Bibliographic Code: 2008GeoRL..3520108O Abstract The near-Earth heliospheric magnetic field intensity, |B|, exhibits a strong solar cycle variation, but returns to the same ``floor'' value each solar minimum. The current minimum, however, has seen |B| drop below previous minima, bringing in to question the existence of a floor, or at the very least requiring a re-assessment of its value. In this study we assume heliospheric flux consists of a constant open flux component and a time-varying contribution from CMEs. In this scenario, the true floor is |B| with zero CME contribution. Using observed CME rates over the solar cycle, we estimate the ``no-CME'' |B| floor at ~4.0 +/- 0.3 nT, lower than previous floor estimates and below |B| observed this solar minimum. We speculate that the drop in |B| observed this minimum may be due to a persistently lower CME rate than the previous minimum, though there are large uncertainties in the supporting observational data. @-------------------------------------------------------------------- Title: International Heliophysical Year 2007: A Report from the UN/NASA Workshop Bangalore, India, 27 November 1 December 2006 Authors: Davila, Joe; Gopalswamy, Nat; Thompson, Barbara; Haubold, Hans J. Bibliographic Code: 2008EM&P..103....9D Abstract The IHY Secretariat and the United Nations Basic Space Science Initiative (UNBSSI) assist scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of IHY/UNBSSI is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, all-sky cameras, etc. around the world to allow global measurements of ionospheric and heliospheric phenomena. The small instrument programme is envisioned as a partnership between instrument providers and instrument hosts in developing nations. The IHY/UNBSSI can facilitate the deployment of several of these networks world-wide. Existing data bases and relevant software tools will be identified to promote space science activities in developing nations. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground-based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides a comprehensive overview of IHY/UNBSSI, its achievements, future plans, and outreach to the 192 Member States of the United Nations as recorded in the UN/NASA workshop in India. @-------------------------------------------------------------------- Title: A comparison of coronal mass ejections identified by manual and automatic methods Authors: Yashiro, S.; Michalek, G.; Gopalswamy, N. Bibliographic Code: 2008AnGeo..26.3103Y Abstract Coronal mass ejections (CMEs) are related to many phenomena (e.g. flares, solar energetic particles, geomagnetic storms), thus compiling of event catalogs is important for a global understanding these phenomena. CMEs have been identified manually for a long time, but in the SOHO era, automatic identification methods are being developed. In order to clarify the advantage and disadvantage of the manual and automatic CME catalogs, we examined the distributions of CME properties listed in the CDAW (manual) and CACTus (automatic) catalogs. Both catalogs have a good agreement on the wide CMEs (width>120°) in their properties, while there is a significant discrepancy on the narrow CMEs (width<=30°): CACTus has a larger number of narrow CMEs than CDAW. We carried out an event-by-event examination of a sample of events and found that the CDAW catalog have missed many narrow CMEs during the solar maximum. Another significant discrepancy was found on the fast CMEs (speed>1000 km/s): the majority of the fast CDAW CMEs are wide and originate from low latitudes, while the fast CACTus CMEs are narrow and originate from all latitudes. Event-by-event examination of a sample of events suggests that CACTus has a problem on the detection of the fast CMEs. @-------------------------------------------------------------------- Title: Coronal mass ejections, type II radio bursts, and solar energetic particle events in the SOHO era Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Mäkelä, P.; Xie, H.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. L. Bibliographic Code: 2008AnGeo..26.3033G Abstract Using the extensive and uniform data on coronal mass ejections (CMEs), solar energetic particle (SEP) events, and type II radio bursts during the SOHO era, we discuss how the CME properties such as speed, width and solar-source longitude decide whether CMEs are associated with type II radio bursts and SEP events. We discuss why some radio-quiet CMEs are associated with small SEP events while some radio-loud CMEs are not associated with SEP events. We conclude that either some fast and wide CMEs do not drive shocks or they drive weak shocks that do not produce significant levels of particle acceleration. We also infer that the Alfvén speed in the corona and near-Sun interplanetary medium ranges from <200 km/s to ~1600 km/s. Radio-quiet fast and wide CMEs are also poor SEP producers and the association rate of type II bursts and SEP events steadily increases with CME speed and width (i.e. energy). If we consider western hemispheric CMEs, the SEP association rate increases linearly from ~30% for 800 km/s CMEs to 100% for >=1800 km/s. Essentially all type II bursts in the decametre-hectometric (DH) wavelength range are associated with SEP events once the source location on the Sun is taken into account. This is a significant result for space weather applications, because if a CME originating from the western hemisphere is accompanied by a DH type II burst, there is a high probability that it will produce an SEP event. @-------------------------------------------------------------------- Title: Solar Activity: Triennial Report of IAU Commission 10 (2006-2009) Authors: Klimchuk, J. A.; van Driel-Gesztelyi, L.; Schrijver, C. J.; Melrose, D. B.; Fletcher, L.; Gopalswamy, N.; Harrison, R. A.; Mandrini, C. H.; Peter, H.; Tsuneta, S.; Vrsnak, B.; Wang, J. Bibliographic Code: 2008arXiv0809.1444K, eprint = 0809.1444 Abstract Commission 10 deals with solar activity in all of its forms, ranging from the smallest nanoflares to the largest coronal mass ejections. This report reviews scientific progress over the roughly two-year period ending in the middle of 2008. This has been an exciting time in solar physics, highlighted by the launches of the Hinode and STEREO missions late in 2006. The report is reasonably comprehensive, though it is far from exhaustive. Limited space prevents the inclusion of many significant results. The report is divided into the following sections: Photosphere and Chromosphere; Transition Region; Corona and Coronal Heating; Coronal Jets; Flares; Coronal Mass Ejection Initiation; Global Coronal Waves and Shocks; Coronal Dimming; The Link Between Low Coronal CME Signatures and Magnetic Clouds; Coronal Mass Ejections in the Heliosphere; and Coronal Mass Ejections and Space Weather. Primary authorship is indicated at the beginning of each section. @-------------------------------------------------------------------- Title: Synthetic radio maps of CME-driven shocks below 4 solar radii heliocentric distance Authors: Schmidt, J. M.; Gopalswamy, N. Bibliographic Code: 2008JGRA..11308104S Abstract We present 2 1/2 D numerical MagnetoHydroDynamic (MHD) simulations of coronal mass ejections (CMEs) in conjunction with plasma simulations of radio emission from the CME-driven shocks. The CME-driven shock extends to an almost spherical shape during the temporal evolution of the CME. Our plasma simulations can reproduce the dynamic spectra of coronal type II radio bursts, with the frequency drift rates corresponding to the shock speeds. We find further, that the CME-driven shock is an effective radio emitter at metric wavelengths, when the CME has reached a heliocentric distance of about two solar radii (R _{$_{\odot}). We apply our simulation results to explain the radio images of type II bursts obtained by radio heliographs, in particular to the banana-shaped images of radio sources associated with fast CMEs. @-------------------------------------------------------------------- Title: Type II Radio Emission and Solar Energetic Particle Events Authors: Gopalswamy, Nat Bibliographic Code: 2008AIPC.1039..196G Abstract Type II radio bursts, solar energetic particle (SEP) events, and interplanetary (IP) shocks all have a common cause, viz., fast and wide (speed >=900 km/s and width >=60°)) coronal mass ejections (CMEs). Deviations from this general picture are observed as (i) lack of type II bursts during many fast and wide CMEs and IP shocks, (ii) slow CMEs associated with type II bursts and SEP events, and (iii) lack of SEP events during many type II bursts. I examine the reasons for these deviations. I also show that ground level enhancement (GLE) events are consistent with shock acceleration because a type II burst is present in every event well before the release of GLE particles and SEPs at the Sun. @-------------------------------------------------------------------- Title: Investigation of CME dynamics in the LASCO field of view Authors: Shanmugaraju, A.; Moon, Y.-J.; Cho, K.-S.; Gopalswamy, N.; Umapathy, S. Bibliographic Code: 2008A&A...484..511S Abstract Context: The speed-distance profile of CMEs is important for understanding the propagation of CMEs.
Aims: Our main aim is to study the initial speed of CMEs in the LASCO field of view and its role in subsequent CME propagation using the acceleration-speed profile. The secondary aim is to obtain the speed growth rate.
Methods: We considered the height-time data of 307 CMEs observed by SOHO/LASCO during January-March 2005. To study the CME speed profile, we used only 116 events for which there were at least 10 height-time measurements in the LASCO field of view. Using this data, we obtained their initial speed, extrapolated initial speed, and growth rate.
Results: The following results were found from this analysis. (i) The initial speed obtained from the first two data points is in the range 24-1208 km s^-1, which is nearly similar to the range of linear speed (67-920 km s^-1) obtained from a least squares fit through the entire h-t data set for each CME. (ii) However, the initial speed or extrapolated initial speed is much better correlated with acceleration and growth rate than the linear speed. (iii) Nearly two thirds of the events (74/116) are found to be accelerating. (iv) The speed growth rate is within the range -0.058 to 0.061 × 10^-3 s^-1, and it decreases with the distance. (v) The final observed distance in the LASCO field of view depends very weakly upon the initial speed, or extrapolated initial speed whereas it depends strongly on the linear speed. The above results demonstrate the role played by the initial speed of the CMEs. @-------------------------------------------------------------------- Title: Properties of Coronal Holes Associated With Large Geomagnetic Storms Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2008AGUSMSP51A..15A Abstract We study the characteristics of 11 equatorial coronal holes (CHs), which resulted in large (minimum Dst index < - 100 nT) geomagnetic storms in the interval 1996 to 2005. These storms were part of the Living with a Star (LWS) Coordinated Data-Analysis Workshop (CDAW) held in March 2005. Using 17 GHz microwave images obtained by the Nobeyama Radio Heliograph (NoRH) and EUV images obtained by the Extreme-ultraviolet Imaging Telescope (EIT), we find the EUV CH area and the CH radio enhancement area are linearly correlated with the solar wind speed. The solar wind speed is also related to the flux expansion factor obtained as the ratio between areas of radio enhancement and EUV CH. We study the temporal sequences of the solar wind parameters and show that the time of CH central meridian passage, peak total magnetic field strength, peak temperature, and peak speed are delayed by -2.5, 0.1, 0.6, 1.1 days from the time of peak CIR density, respectively. @-------------------------------------------------------------------- Title: Effects of solar wind dynamic pressure and preconditioning on large geomagnetic storms Authors: Xie, H.; Gopalswamy, N.; Stcyr, C.; Yashiro, S. Bibliographic Code: 2008AGUSMSM31C..02X Abstract We investigate the effects of solar wind dynamic pressure, Pdyn, and preconditioning in 88 large magnetic storms occurring during solar cycle 23. We have developed an improved model of the Dst profile, based on a modified Burton equation, where additional effects of Pdyn and diminished Dst pressure-correction have been taking into account. On the average, our model predicts the Dst peak values within 9% of observations and gives an overall RMS error of 11%, which is an improvement over those models whose injection functions only depend on the solar wind electric field. The results demonstrate that there is an increase in the Dst peak value when there is a large enhancement of Pdyn during the main phase of a storm. The average increase of the storm intensity is estimated to be 26% for 15 storms with the max (Pdyn) > 15 nPa. We find that the preconditioning in multi-step Dst storms plays no significant role in strengthening the storm intensity, but increases the storm duration. @-------------------------------------------------------------------- Title: Geoeffective Solar Activity: Coronal Mass Ejections, SEP Events and Geomagnetic Storms Over Solar Cycle 23 Authors: M P; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Valtonen, E. Bibliographic Code: 2008AGUSMSH43A..07M Abstract We present updated results for solar cycle 23 on coronal mass ejections (CMEs) and solar energetic particle (SEP) events and their correlations with solar sources and ensuing interplanetary disturbances and geomagnetic storms. The main data set consists of observations over the years 1996--2007 by the LASCO coronagraph and the ERNE particle detector, both on board the SOHO spacecraft. We study the properties of CMEs and the associated geomagnetic storms and the evolution of the properties during solar cycle 23. Especially we are interested with CMEs that are both geoeffective and SEPeffective. Special emphasis will be given to halo CMEs which are the most likely CMEs to be geoeffective. @-------------------------------------------------------------------- Title: Plasma Radiation and Acceleration Effectiveness of CME-driven Shocks Authors: Gopalswamy, N.; Schmidt, J. M. Bibliographic Code: 2008AGUSMSH41A..18G Abstract CME-driven shocks are effective radio radiation generators and accelerators for Solar Energetic Particles (SEPs). We present simulated 3 D time-dependent radio maps of second order plasma radiation generated by CME- driven shocks. The CME with its shock is simulated with the 3 D BATS-R-US CME model developed at the University of Michigan. The radiation is simulated using a kinetic plasma model that includes shock drift acceleration of electrons and stochastic growth theory of Langmuir waves. We find that in a realistic 3 D environment of magnetic field and solar wind outflow of the Sun the CME-driven shock shows a detailed spatial structure of the density, which is responsible for the fine structure of type II radio bursts. We also show realistic 3 D reconstructions of the magnetic cloud field of the CME, which is accelerated outward by magnetic buoyancy forces in the diverging magnetic field of the Sun. The CME-driven shock is reconstructed by tomography using the maximum jump in the gradient of the entropy. In the vicinity of the shock we determine the Alfven speed of the plasma. This speed profile controls how steep the shock can grow and how stable the shock remains while propagating away from the Sun. Only a steep shock can provide for an effective particle acceleration. @-------------------------------------------------------------------- Title: Heating and Kinematics of an Eruptive Prominence Associated with a Fast Coronal Mass Ejection Authors: Gopalswamy, N.; Yashiro, S.; Shibasaki, K. Bibliographic Code: 2008AGUSMSH31C..07G Abstract The fast (1800 km/s) coronal mass ejection (CME) on 2005 July 27 had a bright bubble-shaped prominence core observed by the Nobeyama Radioheliograph (NoRH) in microwaves (17 and 34 GHz), TRACE at 171 A, and the Extreme-ultraviolet Imaging Telescope (EIT) on board SOHO. NoRH has the largest field of view among the non- white light instruments, so the prominence could be tracked until it reached a height of about 0.75 solar radii from the limb. The prominence remained optically thick at both 17 and GHz, even though it was significantly heated. Comparison with TRACE observations suggest that the prominence was heated in individual fibers within the prominence, making it multi-thermal plasma. The prominence maintained its overall shape as it entered into the field of view of SOHO/LASCO coronagraphs with a speed of about 1400 km/s, so the height-time history could be studied over a distance of more than 20 solar radii from the Sun. NoRH data indicated that the initial acceleration was extremely high (about1.4 km/s/s). During the slow-rise phase of the prominence, EUV loops overlying the prominence also moved out, which when combines with CME leading-edge measurements from LASCO/C2 yielded an acceleration of about 300 m/s/s. This was comparable to the average acceleration of the prominence over the same height range. When we consider the just the LASCO field of view, both the prominence core and the CME leading edge showed deceleration, but to vastly different extents (-32 m/s/s for the CME leading edge compared to -3 m/s/s for the prominence core). Our preliminary conclusion is that the prominence was insulated from interacting with the non-CME ambient medium, which might explain the weaker slowing down of the prominence. @-------------------------------------------------------------------- Title: Poor CME Productivity in Active Region 10960 Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S. Bibliographic Code: 2008AGUSMSH31A..03Y Abstract Larger flares are generally likely to be associated with coronal mass ejections (CMEs), but there are some CME- poor active regions, which produce many large flares without associated CMEs. We present once such active region NOAA 10960, which produced 10 M-class flares during the disk passage. We examined their CME associations using coronagraph observations obtained by LASCO on SOHO and SECCHI on STEREO. The three coronagraph observations help us to determine whether or not a flare has the associated CME. We found that two out of 10 M-class flares were associated with the CMEs. The rate (20%) is low compared to the average CME association rate (50%) of M-class flares during the solar cycle 23. In addition, the associated CMEs are slow (337 km/s and 208 km/s); further strengthening the conclusion that AR 10960 is CME-poor. We consider various possibilities to explain why the active region is CME-poor. @-------------------------------------------------------------------- Title: Average Thickness of Magnetosheath Upstream of Magnetic Clouds at 1 AU versus Solar Longitude of Source Authors: Lepping, R. P.; Wu, C.-C.; Gopalswamy, N.; Berdichevsky, D. B. Bibliographic Code: 2008SoPh..248..125L Abstract Starting with a large number ( N=100) of Wind magnetic clouds (MCs) and applying necessary restrictions, we find a proper set of N=29 to investigate the average ecliptic plane projection of the upstream magnetosheath thickness as a function of the longitude of the solar source of the MCs, for those cases of MCs having upstream shock waves. A few of the obvious restrictions on the full set of MCs are the need for there to exist a driven upstream shock wave, knowledge of the MC's solar source, and restriction to only MCs of low axial latitudes. The analysis required splitting this set into two subsets according to average magnetosheath speed: slow/average (300 - 500 km s^-1) and fast (500 - 1100 km s^-1) speeds. Only the fast set gives plausible results, where the estimated magnetosheath thickness (Delta S) goes from 0.042 to 0.079 AU (at 1 AU) over the longitude sector of 0° (adjusted source-center longitude of the average magnetic cloud) to 40° off center (East or West), based on N=11 appropriate cases. These estimates are well determined with a sigma ( sigma) for the fit of 0.0055 AU, where sigma is effectively the same as sqrt{} (chi-squared) for the appropriate quadratic fit. The associated linear correlation coefficient for Delta S versus |Longitude| was very good (c.c.=0.93) for the fast range, and Delta S at 60° longitude is extrapolated to be 2.7 times the value at 0°. For the slower speeds we obtain the surprising result that Delta S is typically more-or-less constant at 0.040±0.013 AU at all longitudes, indicating that the MC as a driver, when moving close to the normal solar wind speed, has little influence on magnetosheath thickness. In some cases, the correct choice between two candidate solar-source longitudes for a fast MC might be made by noting the value of the observed Delta S just upstream of the MC. Also, we point out that, for the 29 events, the average sheath speed was well correlated with the quantity Delta V[=(< V _MC>-< V _UPSTREAM>)], and also with both < V _MC> and < V _MC,T>, where < V _MC> is the first one-hour average of the MC speed, < V _MC,T> is the average MC speed across the full MC, and < V _UPSTREAM> is a five-hour average of the solar wind speed just upstream of the shock. @-------------------------------------------------------------------- Title: Space Weather Application Using Projected Velocity Asymmetry of Halo CMEs Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2008SoPh..248..113M, eprint = 0801.1977 Abstract Halo coronal mass ejections (HCMEs) originating from regions close to the center of the Sun are likely to be responsible for severe geomagnetic storms. It is important to predict geoeffectiveness of HCMEs by using observations when they are still near the Sun. Unfortunately, coronagraphic observations do not provide true speeds of CMEs because of projection effects. In the present paper, we present a new technique to allow estimates of the space speed and approximate source location using projected speeds measured at different position angles for a given HCME (velocity asymmetry). We apply this technique to HCMEs observed during 2001 2002 and find that the improved speeds are better correlated with the travel times of HCMEs to Earth and with the magnitudes of ensuing geomagnetic storms. @-------------------------------------------------------------------- Title: Effects of solar wind dynamic pressure and preconditioning on large geomagnetic storms Authors: Xie, H.; Gopalswamy, N.; St. Cyr, O. C.; Yashiro, S. Bibliographic Code: 2008GeoRL..3506S08X Abstract We investigate the effects of solar wind dynamic pressure, P _dyn, and preconditioning in 88 large magnetic storms (Dst < -100 nT) occurring during solar cycle 23. We have developed an improved model of the Dst profile, based on a modified Burton equation, where additional effects of P _dyn and diminished Dst pressure-correction have been taking into account. On the average, our model predicts the Dst peak values within 9% of observations and gives an overall RMS error of 11%, which is an improvement over those models whose injection functions only depend on the solar wind electric field. The results demonstrate that there is an increase in the Dst peak value when there is a large enhancement of P _dyn during the main phase of a storm. The average increase of the storm intensity is estimated to be 26% for 15 storms with the max (P _dyn) > 15 nPa. We find that the preconditioning in multi-step Dst storms plays no significant role in strengthening the storm intensity, but increases the storm duration. @-------------------------------------------------------------------- Title: Solar sources and geospace consequences of interplanetary magnetic clouds observed during solar cycle 23 [ Erratum: 2009JASTP..71.1005G ] Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P. Bibliographic Code: 2008JASTP..70..245G Abstract We present results of a statistical investigation of 99 magnetic clouds (MCs) observed during 1995-2005. The MC-associated coronal mass ejections (CMEs) are faster and wider on the average and originate within ±30o from the solar disk center. The solar sources of MCs also followed the butterfly diagram. The correlation between the magnetic field strength and speed of MCs was found to be valid over a much wider range of speeds. The number of south-north (SN) MCs was dominant and decreased with solar cycle, while the number of north-south (NS) MCs increased confirming the odd-cycle behavior. Two-thirds of MCs were geoeffective; the Dst index was highly correlated with speed and magnetic field in MCs as well as their product. Many (55%) fully northward (FN) MCs were geoeffective solely due to their sheaths. The non-geoeffective MCs were slower (average speed ), had a weaker southward magnetic field (average ), and occurred mostly during the rise phase of the solar activity cycle. @-------------------------------------------------------------------- Title: Radio-Quiet Fast and Wide Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; Xie, H.; Akiyama, S.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A.; Bougeret, J.-L. Bibliographic Code: 2008ApJ...674..560G Abstract We report on the properties of radio-quiet (RQ) and radio-loud (RL) coronal mass ejections (CMEs) that are fast and wide (FW). RQ CMEs lack type II radio bursts in the metric and decameter-hectometric (DH) wavelengths. RL CMEs are associated with metric or DH type II bursts. We found that ~40% of the FW CMEs from 1996 to 2005 were RQ. The RQ CMEs had an average speed of 1117 km s^-1 compared to 1438 km s^-1 for the RL, bracketing the average speed of all FW CMEs (1303 km s^-1). The fraction of full halo CMEs (apparent width=360^deg) was the largest for the RL CMEs (60%), smallest for the RQ CMEs (16%), and intermediate for all FW CMEs (42%). The median soft X-ray flare size for the RQ CMEs (C6.9) was also smaller than that for the RL CMEs (M3.9). About 55% of RQ CMEs were back sided, while the front-sided ones originated close to the limb. The RL CMEs originated generally on the disk with only ~25% being back sided. The RQ FW CMEs suggest that the Alfvén speed in the low-latitude outer corona can often exceed 1000 km s^-1 and can vary over a factor of >=3. None of the RQ CMEs was associated with large solar energetic particle events, which is useful information for space weather applications. @-------------------------------------------------------------------- Title: Spatial Relationship between Solar Flares and Coronal Mass Ejections Authors: Yashiro, S.; Michalek, G.; Akiyama, S.; Gopalswamy, N.; Howard, R. A. Bibliographic Code: 2008ApJ...673.1174Y, eprint = 0710.3054 Abstract We report on the spatial relationship between solar flares and coronal mass ejections (CMEs) observed during 1996-2005 inclusive. We identified 496 flare-CME pairs considering limb flares (distance from central meridian >=45°) with soft X-ray flare size >=C3 level. The CMEs were detected by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO). We investigated the flare positions with respect to the CME span for the events with X-class, M-class, and C-class flares separately. It is found that the most frequent flare site is at the center of the CME span for all the three classes, but that frequency is different for the different classes. Many X-class flares often lie at the center of the associated CME, while C-class flares widely spread to the outside of the CME span. The former is different from previous studies, which concluded that no preferred flare site exists. We compared our result with the previous studies and conclude that the long-term LASCO observation enabled us to obtain the detailed spatial relation between flares and CMEs. Our finding calls for a closer flare-CME relationship and supports eruption models typified by the CSHKP magnetic reconnection model. @-------------------------------------------------------------------- Title: Origin of Geoeffective Coronal Mass Ejections during Solar Cycle 23 Authors: Gopalswamy, Nat Bibliographic Code: 2008cosp...37.1057G Abstract The importance of coronal mass ejections (CMEs) in causing major geomagnetic storms has been well established in the 1990s due to the southward magnetic field contained in the sheath and ejecta portions of the interplanetary (IP) counterparts of CMEs (or ICMEs). The nice ordering of the internal structure of ICMEs revealed by in situ observations (shock followed by sheath and ejecta with or without flux rope structure) is far from clear at the Sun because the remote sensing technique reveals only the mass content of the CME rather than the magnetic properties. Nevertheless, there have been several attempts to relate the internal structure of CMEs to the magnetic properties of the source active regions on the Sun. For example, the filament marking the polarity inversion lines have been shown to be in the same direction as the axis of the flux rope observed in the IP medium. Such a correspondence is supported by the close relationship found between post eruption arcades at the Sun and the IP magnetic clouds (i.e., flux ropes). However, not all ICMEs or flux ropes, which may very well be an observational effect. The number of ICMEs with flux rope structure observed near Earth varies with the solar cycle and there are indications that the global magnetic field of the Sun and the active region field have varying contribution in deciding the magnetic properties of ICMEs. The sheath is most likely related to the global field of the Sun, while the ejecta is related to the active region magnetic field. The sheath is created by the ejecta portion as it compresses the overlying global field. We are still not in a position to resolve the sheath and ejecta portions of CMEs near the Sun, especially in those heading towards Earth and causing geomagnetic storms. Nevertheless, CME observations can help us infer the strength and orientation of the magnetic field in ICMEs, which are key parameters deciding the occurrence and strength of geomagnetic storms. This paper summarizes the current developments in the understanding of the CME-ICME relationship using the complete data sets on CMEs, ICMEs, and geomagnetic storms over one complete solar cycle that just ended in December 2007. @-------------------------------------------------------------------- Title: Width of Radio-Loud and Radio-Quiet CMEs Authors: Michalek, G.; Gopalswamy, N.; Xie, H. Bibliographic Code: 2007SoPh..246..409M, eprint = 0710.4519 Abstract In the present paper we report on the difference in angular sizes between radio-loud and radio-quiet CMEs. For this purpose we compiled these two samples of events using Wind/WAVES and SOHO/LASCO observations obtained during 1996 - 2005. We show that the radio-loud CMEs are almost twice as wide as the radio-quiet CMEs (considering expanding parts of CMEs). Furthermore, we show that the radio-quiet CMEs have a narrow expanding bright part with a large extended diffusive structure. These results were obtained by measuring the CME widths in three different ways. @-------------------------------------------------------------------- Title: Prediction of Space Weather Using an Asymmetric Cone Model for Halo CMEs Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2007SoPh..246..399M, eprint = 0710.4372 Abstract Halo coronal mass ejections (HCMEs) are responsible of the most severe geomagnetic storms. A prediction of their geoeffectiveness and travel time to Earth's vicinity is crucial to forecast space weather. Unfortunately, coronagraphic observations are subjected to projection effects and do not provide true characteristics of CMEs. Recently, Michalek ( Solar Phys. 237, 101, 2006) developed an asymmetric cone model to obtain the space speed, width, and source location of HCMEs. We applied this technique to obtain the parameters of all front-sided HCMEs observed by the SOHO/LASCO experiment during a period from the beginning of 2001 until the end of 2002 (solar cycle 23). These parameters were applied for space weather forecasting. Our study finds that the space speeds are strongly correlated with the travel times of HCMEs to Earth's vicinity and with the magnitudes related to geomagnetic disturbances. @-------------------------------------------------------------------- Title: Correction to ``Solar and interplanetary sources of major geomagnetic storms (Dst <= -100 nT) during 1996-2005'' Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.; Huttunen, E.; Kasper, J.; Nitta, N. V.; Poomvises, W.; Thompson, B. J.; Wu, C.-C.; Yashiro, S.; Zhukov, A. N. Bibliographic Code: 2007JGRA..11212103Z Abstract Abstract Available from http://www.agu.org @-------------------------------------------------------------------- Title: Division II / Working Group International Collaboration in Space Weather Authors: Webb, David F.; Gopalswamy, Nat; Liu, William; Sibeck, David G.; Schmieder, Brigitte; Wang, Jingxiu; Wang, Chi Bibliographic Code: 2007IAUTB..26..107W Abstract The IAU Division II WG on International Collaboration in Space Weather has as its main goal to help coordinate the many activities related to space weather at an international level. The WG currently includes the international activities of the International Heliospheric Year (IHY), the International Living with a Star (ILWS) program, the CAWSES (Climate and Weather of the Sun-Earth System) Working Group on Sources of Geomagnetic Activity, and Space Weather Studies in China. The coordination of IHY activities within the IAU is led by Division II under this working group. The focus of this half-day meeting was on the activities of the IHY program. About 20 people were in attendance. The Chair of the WG, David F. Webb, gave a brief introduction noting that the meeting would have two parts: first, a session on IHY activities emphasizing IHY Regional coordination and, second, a general discussion of the other programs of the WG involving international Space Weather activities. @-------------------------------------------------------------------- Title: A Catalog of Halo Coronal Mass Ejections from SOHO Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Vourlidas, A.; Howard, R. A.; Schmidt, J. Bibliographic Code: 2007AGUFMSH51A0262G Abstract Halo coronal mass ejections (CMEs) have become one of the important subsets of CMEs, thanks to the extensive data accumulated by the Solar and Heliospheric Observatory (SOHO) mission. Halo CMEs are inherently more energetic on the average, so they are important for producing geomagnetic storms and solar energetic particle events (Gopalswamy et al., 2007). One of the key aspects halo CMEs is their source location, which decides whether the halo is symmetric or not. When the source is closer to the solar limb, the CMEs tend to become asymmetric halos or partial halos. Halos with their sources nearer to the limb are also the fastest (because of projection effects), but are less geoeffective due to the glancing blow they deliver to Earth's magnetosphere. Thus, providing source information to all halo CMEs in a separate catalog is useful information in selecting candidate geoeffective CMEs. The second important quantity of CMEs is the space speed, which decides the arrival time of CMEs at Earth. Since CMEs change their width during their early evolution, it is not easy to correct for the projection effects from the geometry of eruption. One way of correcting for projection effects is to use a cone model for CMEs. There are at least 3 published cone models, all of them seem to remove the projection effects reasonably well. The geometric parameters of the cone are determined using different methods in each model. Here we use the model by Xie et al. (2004), which has generally less restrictions, and hence can be applied to more number of halos. This paper provides a brief description of the catalog of halo CMEs, which resides at the CDAW Data Center, NASA Goddard Space Flight Center, Greenbelt, MD. The catalog enhances the existing data services at the CDAW Data Center, which participates in the Virtual Solar Observatory. Work supported by NASA's Virtual Observatories for Solar and Space Physics Data Program. References Gopalswamy et al., JGR, 112, A06112, doi:10.1029/2006JA012149, 2007 Xie et al. JGR, 109, A03109, doi: 10.1029/2003JA010226, 2004 @-------------------------------------------------------------------- Title: Synoptic Solar Radio Burst Source Directions Derived by the Ulysses URAP Investigation Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Hess, R. A.; Reiner, M. J.; Hoang, S. Bibliographic Code: 2007AGUFMSH41A0308M Abstract The Unified Radio and Plasma (URAP) investigation is one of 10 instruments on the Ulysses spacecraft. Ulysses, with its highly inclined orbit around the sun, provides URAP with a unique perspective on solar radio bursts, which are usually emitted at low heliolatitudes as the electron sources move outward from the sun. These radio bursts provide positional information relating to interplanetary coronal mass ejections (type II radio bursts), the initiation of CMEs (type III-L bursts), and solar flares (type III bursts). In this presentation, we use the routine radio direction-finding data from URAP to track radio bursts and locate their sources when Ulysses is near perihelion. Plots of these data are available on the URAP Goddard Space Flight Center web site (for example, http://urap.gsfc.nasa.gov/cgi/giffer?date=20070726&PLOT_TYPE= DIRFIND), as are ASCII data files. The results shown are derived from fitting the spin-plane antenna data only; we compare the source directions so derived to the more accurate determinations made by fitting to both URAP antennas. The accuracy of the radio source directions to identify flare locations, determine solar wind densities remotely, etc., will be compared to previously published determinations. Applications to Wind Waves and STEREO Waves data, for which the spacecraft are in-ecliptic, will be addressed briefly. @-------------------------------------------------------------------- Title: A Statistical Study of the Ejecta - Shock Standoff Distance of Geoeffective Events Authors: Lara, A.; Gopalswamy, N.; Yashiro, S.; Borgazzi, A. I. Bibliographic Code: 2007AGUFMSH31A0236L Abstract e study the interplanetary transport of 57 coronal mass ejections (CMEs), which are part of the events responsible for large geomagnetic storms of solar cycle 23 listed in the CDAW database. The interplanetary counterparts of these CMEs (ICMEs) were shock-driving and have caused intense (Dst < -100) geomagnetic storms. We study the statistical behavior of the standoff distance and time between the ICME and the shock. We divided our events into two groups, 1) events where there is likely a one-to-one relationship between the CMEs and ICMEs (unique events) and 2) events where multiple CMEs may be associated with a single ICME. We find that the standoff time of the unique events follows a normal distribution whit a mean of 7.6 hr. and a sigma sigma = 4.7 hr. The standoff distance of unique events also follows a normal distribution with a mean of ~ 0.1 AU and a sigma of ~ 0.05 AU. We did not found any relationship between the position of the AR,associated to the low coronal CME activity, and the standoff distance. On the other hand there seems to be a linear relationship between the CME speed and the standoff distance. @-------------------------------------------------------------------- Title: Synthetic Radio Maps of CMEs up to 24 Solar Radii Heliocentric Distance Authors: Schmidt, J. M.; Gopalswamy, N. Bibliographic Code: 2007AGUFMSH23B..01S Abstract We present numerical MagnetoHydroDynamic (MHD) simulations of coronal mass ejections (CMEs) and plasma simulations of radio emission from the CME-driven shocks. The simulations correspond to an idealized system, where rotational symmetry around the rotation axis of the Sun is assumed. So the CME has a flux rope structure that extends like a torus around the symmetry axis, i.e. no geometrical effects due to a connection of footpoints of the flux rope with the solar surface are considered. The CME-driven shock extends to an almost spherical shape during the temporal evolution of the CME. We find that our simulations can reproduce the dynamic spectra of coronal radio type II bursts, where the frequency drift rates correspond to the CME-driven shock speeds. We find further, that the CME-driven shock is an effective radio emitter at metric wavelengths, when the CME has reached a heliocentric distance of about two solar radii (R\odot). Towards the center of the CME, where the plasma emission frequency drops significantly due to an over expansion of the core of the CME, the emission is eclipsed for a fixed frequency radio receiver. We apply our simulation results to explain the radio images of type II bursts obtained by radio heliographs, in particular to the banana-shaped images of radio sources associated with fast CMEs. The shock at the rear part of the CME can become an effective radio emitter, where reconnection of magnetic field lines leads to enhanced gradients of magnetic fields. Yet, this emission is usually at lower frequencies than that at the shock front. We apply our kinetic and analytic model of plasma radiation further to MHD simulations of CMEs in 3D. The differences between the 3D and 2D cases are discussed. @-------------------------------------------------------------------- Title: Solar and interplanetary sources of major geomagnetic storms (Dst <= -100 nT) during 1996-2005 Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.; Huttunen, E.; Kasper, J. C.; Nitta, N. V.; Poomvises, W.; Thompson, B. J.; Wu, C.-C.; Yashiro, S.; Zhukov, A. N. Bibliographic Code: 2007JGRA..11210102Z Abstract We present the results of an investigation of the sequence of events from the Sun to the Earth that ultimately led to the 88 major geomagnetic storms (defined by minimum Dst <= -100 nT) that occurred during 1996-2005. The results are achieved through cooperative efforts that originated at the Living with a Star (LWS) Coordinated Data-Analysis Workshop (CDAW) held at George Mason University in March 2005. On the basis of careful examination of the complete array of solar and in situ solar wind observations, we have identified and characterized, for each major geomagnetic storm, the overall solar-interplanetary (solar-IP) source type, the time, velocity, and angular width of the source coronal mass ejection (CME), the type and heliographic location of the solar source region, the structure of the transient solar wind flow with the storm-driving component specified, the arrival time of shock/disturbance, and the start and ending times of the corresponding IP CME (ICME). The storm-driving component, which possesses a prolonged and enhanced southward magnetic field (B _s), may be an ICME, the sheath of shocked plasma (SH) upstream of an ICME, a corotating interaction region (CIR), or a combination of these structures. We classify the Solar-IP sources into three broad types: (1) S-type, in which the storm is associated with a single ICME and a single CME at the Sun; (2) M-type, in which the storm is associated with a complex solar wind flow produced by multiple interacting ICMEs arising from multiple halo CMEs launched from the Sun in a short period; (3) C-type, in which the storm is associated with a CIR formed at the leading edge of a high-speed stream originating from a solar coronal hole (CH). For the 88 major storms, the S-type, M-type, and C-type events number 53 (60%), 24 (27%), and 11 (13%), respectively. For the 85 events for which the surface source regions could be investigated, 54 (63%) of the storms originated in solar active regions, 11 (13%) in quiet Sun regions associated with quiescent filaments or filament channels, and 11 (13%) were associated with coronal holes. Remarkably, nine (11%) CME-driven events showed no sign of eruptive features on the surface or in the low corona (e.g., no flare, no coronal dimming, and no loop arcade, etc.), even though all the available solar observations in a suitable time period were carefully examined. Thus while it is generally true that a major geomagnetic storm is more likely to be driven by a frontside fast halo CME associated with a major flare, our study indicates a broad distribution of source properties. The implications of the results for space weather forecasting are briefly discussed. @-------------------------------------------------------------------- Title: Energetic Phenomena on the Sun Authors: Gopalswamy, Nat Bibliographic Code: 2007AIPC..919..275G Abstract Solar flares, coronal mass ejections (CMEs), solar energetic particles (SEPs), and fast solar wind represent the energetic phenomena on the Sun. Flares and CMEs originate from closed magnetic field structures on the Sun typically found in active regions and quiescent filament regions. On the other hand, fast solar wind originates from open field regions on the Sun, identified as coronal holes. Energetic particles are associated with flares, CMEs, and fast solar wind, but the ones associated with CMEs are the most intense. The energetic phenomena have important consequences in the heliosphere and contribute significantly to adverse space weather. This paper provides an over view of the energetic phenomena on the Sun including their origin interplanetary propagation and space weather consequences. @-------------------------------------------------------------------- Title: The Early Life Of A Coronal Mass Ejection From SECCHI And SOHO Observations Authors: Gopalswamy, N.; Yashiro, S.; Davila, J. M.; Howard, R. A.; SECCHI/COR1 Team Bibliographic Code: 2007AAS...210.2813G Abstract One of the key advantages of STEREO/SECCHI is the inner coronagraph (COR1), which can observe CMEs in the coronal region where CMEs attain their maximum acceleration. The first CME observed by COR1 was on 2006 December 30. The CME was also observed by the C2 and C3 coronagraphs of SOHO. We compare the morphological and height-time histories between COR1 and SOHO/LASCO data. We find that the flux rope structure evolves significantly between the COR1 and LASCO/C2 FOVs, although we can track features to get a continuous height-time history of the CME. We find excellent agreement between the two sets of data which could be combined to obtain the kinematic properties of the CME. We also superposed a STEREO/COR1 image of the CME on a STEREO/EUVI image and SOHO/C2 image to compare the solar origin and morphology. The CME originated from the southwest quadrant of the Sun and was of flux-rope type moving with an average speed of 200 km/s and an acceleration of 6 m/s/s, with a characteristic two-ribbon structure and an extended post-eruption arcade. In addition to the similarity in CME features, there was excellent correspondence between the outlying streamers in the two coronagraph images. @-------------------------------------------------------------------- Title: Geoeffectiveness of halo coronal mass ejections Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibliographic Code: 2007JGRA..11206112G Abstract We studied the geoeffectiveness, speed, solar source, and flare association of a set of 378 halo coronal mass ejections (CMEs) of cycle 23 (1996-2005, inclusive). We compiled the minimum Dst values occurring within 1-5 days after the CME onset. We compared the distributions of such Dst values for the following subsets of halo CMEs: disk halos (within 45 deg from disk center), limb halos (beyond 45 degrees but within 90 deg from disk center), and backside halo CMEs. Defining that a halo CME is geoeffective if it is followed by Dst <= -50 nT, moderately geoeffective if -50 nT < Dst < -100 nT, and strongly geoeffective if Dst <= -100 nT, we find that the disk halos are followed by strong storms, limb halos are followed by moderate storms, and backside halos are not followed by significant storms. The Dst distribution for a random sample is nearly identical to the case of backside halos. About 71% of all frontside halos are geoeffective, supporting the high rate of geoeffectiveness of halo CMEs. A larger fraction (75%) of disk halos are geoeffective. Intense storms are generally due to disk halos and the few intense storms from limb halos occur only in the maximum and declining phases. Most intense storms occur when there are successive CMEs. The delay time between CME onset and minimum Dst value is the smallest for limb halos, suggesting that the sheath is geoeffective in these cases. The geoeffectiveness rate has prominent dips in 1999 and 2002 (the beginning and end years of the solar maximum phase). The numbers of all frontside and geoeffective frontside halos show a triple peak structure similar to the number of intense geomagnetic storms. The difference in flare sizes among geoeffective and nongeoeffective halos is not significant. The nongeoeffective CMEs are generally slower and have more easterly or limbward solar sources compared to the geoeffective ones; source location and speed are the most important parameters for geoeffectiveness. @-------------------------------------------------------------------- Title: Why Some Fast and Wide Coronal Mass Ejections are Radio-quiet? Authors: Gopalswamy, N.; Xie, H.; Aguilar-Rodriguez, E.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. L. Bibliographic Code: 2007AAS...210.5801G Abstract The radio-quiet CMEs lack type II radio burst association in the metric and decameter-hectometric (DH) wavelengths. We compiled CMEs faster than 900 km/s and wider than 60 degrees and checked against metric and interplanetary type II bursts and found that about one third of them were radio-quiet. We compared the radio-quiet CMEs with the radio-loud ones occurring over the same study period (1996-2005). The radio-quiet and radio-loud CMEs had average speeds of 1129 and 1524 km/s, respectively bracketing the average speed of all FW CMEs (1303 km/s). The width distributions also showed a similar behavior: the fraction of halo and partial halo CMEs was the largest for the radio-loud CMEs (54%), smallest for the radio-quiet CMEs (18%) and intermediate for all fast and wide CMEs (42%). The majority of radio-quiet CMEs (55%) were back-sided; most of the frontsided ones also originated close to the limb. This is in contrast to the radio-loud CMEs which originated generally on the disk with only a small fraction (13%) was back-sided. The average flare size was also slightly smaller for the radio-quiet CMEs compared to that of radio-loud CMEs. Back-sided and limb CMEs have only part of the shock surface visible to the observer. This seems to be an important factor deciding whether a CME is radio quiet. @-------------------------------------------------------------------- Title: IHY - An International Cooperative Program Authors: Rabello-Soares, M. Cristina; Davila, J.; Gopalswamy, N.; Thompson, B. Bibliographic Code: 2007AAS...210.5701R Abstract The International Heliophysical Year (IHY) in 2007/2008 involves thousands of scientists representing over 70 nations. It consists of four distinct elements that will be described here. Taking advantage of the large amount of heliophysical data acquired routinely by a vast number of sophisticated instruments aboard space missions and at ground-based observatories, IHY aims to develop the basic science of heliophysics through cross-disciplinary studies of universal processes by means of Coordinated Investigation Programs (CIPs). The second component is in collaboration with the United Nations Basic Space Science Initiative (UNBSSI) and consists of the deployment of arrays of small, inexpensive instruments such as magnetometers, radio antennas, GPS receivers, etc. around the world to provide global measurements. An important aspect of this partnership is to foster the participation of developing nations in heliophysics research. IHY coincides with the commemoration of 50 years of the space age that started with launch of Sputnik on October 4, 1957 and it is on the brink of a new age of space exploration where the Moon, Mars and the outer planets will be the focus of the space programs in the next years. As a result, it presents an excellent opportunity to create interest for science among young people with the excitement of discovery of space. The education and outreach program forms another cornerstone of IHY. Last but not least, an important part of the IHY activities, its forth component, is to preserve the history and memory of IGY 1957. @-------------------------------------------------------------------- Title: Commission 10: Solar Activity Authors: Melrose, Donald B.; Klimchuk, James A.; Benz, A. O.; Craig, I. J. D.; Gopalswamy, N.; Harrison, R. A.; Kozlovsky, B. Z.; Poletto, G.; Schrijver, K. J.; van Driel-Gesztelyi, L.; Wang, J.-X. Bibliographic Code: 2007IAUTA..26...75M Abstract Commission 10 aims at the study of various forms of solar activity, including networks, plages, pores, spots, fibrils, surges, jets, filaments/prominences, coronal loops, flares, coronal mass ejections (CMEs), solar cycle, microflares, nanoflares, coronal heating etc., which are all manifestation of the interplay of magnetic fields and solar plasma. Increasingly important is the study of solar activities as sources of various disturbances in the interplanetary space and near-Earth "space weather".Over the past three years a major component of research on the active Sun has involved data from the RHESSI spacecraft. This review starts with an update on current and planned solar observations from spacecraft. The discussion of solar flares gives emphasis to new results from RHESSI, along with updates on other aspects of flares. Recent progress on two theoretical concepts, magnetic reconnection and magnetic helicity is then summarized, followed by discussions of coronal loops and heating, the magnetic carpet and filaments. The final topic discussed is coronal mass ejections and space weather.The discussions on each topic is relatively brief, and intended as an outline to put the extensive list of references in context.The review was prepared jointly by the members of the Organizing Committee, and the names of the primary contributors to the various sections are indicated in parentheses. @-------------------------------------------------------------------- Title: The International Heliophysical Year Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J. Bibliographic Code: 2007RoAJ...17....3D Abstract @-------------------------------------------------------------------- Title: Energetic Particles Related with Coronal and Interplanetary Shocks Authors: Gopalswamy, N. Bibliographic Code: 2007LNP...725..139G Abstract Acceleration of electrons and ions at the Sun is discussed in the framework of CME-driven shocks. Based on the properties of coronal mass ejections associated with type II bursts at various wavelengths, the possibility of a unified approach to the type II phenomena is suggested. Two aspects of primary importance to shock accelerations are: (1) Energy of the driving CME and (2) the conditions in the medium that supports shock propagation. The high degree of overlap between CMEs associated with large solar energetic particle events and type II bursts occurring at all wavelengths underscores the importance of CME energy in driving shocks far into the interplanetary medium. Presence of preceding CMEs can alter the conditions in the ambient medium, which is shown to influence the intensity of large solar energetic particle events. Both statistical evidence and case studies are presented that underscore the importance of the ambient medium. @-------------------------------------------------------------------- Title: The United Nations Basic Space Science Initiative for IHY 2007 Authors: Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Haubold, Hans Bibliographic Code: 2007IAUSS...5..295G Abstract @-------------------------------------------------------------------- Title: The United Nations Basic Space Science Initiative: the TRIPOD concept Authors: Kitamura, Masatoshi; Wentzel, Don; Henden, Arne; Bennett, Jeffrey; Al-Naimiy, H. M. K.; Mathai, A. M.; Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Webb, David; Haubold, Hans Bibliographic Code: 2007IAUSS...5..277K, eprint = physics/0610149 Abstract Since 1990, the United Nations is annually holding a workshop on basic space science for the benefit of the worldwide development of astronomy. Additional to the scientific benefits of the workshops and the strengthening of international cooperation, the workshops lead to the establishment of astronomical telescope facilities through the Official Development Assistance (ODA) of Japan. Teaching material, hands-on astrophysics material, and variable star observing programmes had been developed for the operation of such astronomical telescope facilities in an university environment. This approach to astronomical telescope facility, observing programme, and teaching astronomy has become known as the basic space science TRIPOD concept. Currently, a similar TRIPOD concept is being developed for the International Heliophysical Year 2007, consisting of an instrument array, data taking and analysis, and teaching space science. @-------------------------------------------------------------------- Title: The CME-productivity associated with flares from two active regions Authors: Akiyama, S.; Yashiro, S.; Gopalswamy, N. Bibliographic Code: 2007AdSpR..39.1467A Abstract We report on two flare-productive adjacent active regions (ARs), with different levels of coronal mass ejection (CME) association. AR 10039 and AR 10044 produced strong X-ray flares during their disk passages. We examined the CME association rate of X-ray flares and found it to be different between the two ARs. AR 10039 was CME-rich with 72% association with flares, while AR 10044 was CME-poor with an association rate of only 14%. CMEs from the CME-rich AR were faster and wider than the ones from the CME-poor AR. The flare activity of AR 10044 was temporally concentrated over a short interval and spatially localized over a compact area between the major sun spots. We suggest that different pre-eruption evolution and magnetic configuration in the two regions might have contributed to the difference between the two ARs. @-------------------------------------------------------------------- Title: Consequences of Coronal Mass Ejections in the Heliosphere Authors: Gopalswamy, N. Bibliographic Code: 2006SunGe...1b...5G Abstract Coronal mass ejections (CMEs) are the most energetic events in the heliosphere. They carry large amounts of coronal magnetic fields and plasma with them and drive large-scale interplanetary shocks. The CMEs and shock have significant consequences at various locations in the heliosphere, including the production of intense geomagnetic storms and large energetic particle events. CMEs form merged interaction regions in the heliosphere, which act as magnetic barriers for the galactic cosmic rays entering the heliosphere. After a brief summary of the observed properties of CMEs at the Sun, I discuss the properties of the interplanetary CMEs (ICMEs) and their connection to shocks, radio bursts, solar energetic particles and the modulation of galactic cosmic rays. @-------------------------------------------------------------------- Title: Radio Observations of Solar Eruptions Authors: Gopalswamy, N. Bibliographic Code: 2006spnr.conf...81G Abstract Coronal mass ejections (CMEs) are composed of multithermal plasmas, which make them produce different radio signatures at different wavelengths. The prominence core of CMEs are of the lowest temperature and hence optically thick at microwave frequencies and hence are readily observed. The Nobeyama Radioheliograph has exploited this fact and observed a large number of prominence eruptions over most of solar cycle 23 and parts of cycle 22. This paper reviews recent studies on prominence eruptions and their contributions for understanding the CME phenomenon. In particular, the following issues are discussed: (i) the statistical and physical relationship between CMEs and the radio prominence eruptions, and how this relationship manifests as a function of the solar cycle; (ii) The asymmetry of prominence eruptions between northern and southern hemispheres; (iii) the relationship between prominence eruptions and CME cores; (iv) the implications of the cessation of high-latitude PEs before the reversal of the global solar magnetic field, and (v) the implications of the high-latitude PEs and CMEs for the modulation of galactic cosmic rays. Finally, the importance of the Nobeyama Radioheliograph data to future missions such as STEREO and Solar-B are discussed. @-------------------------------------------------------------------- Title: Relationships Among Magnetic Clouds, CMES, and Geomagnetic Storms Authors: Wu, C. C.; Lepping, R. P.; Gopalswamy, N. Bibliographic Code: 2006SoPh..239..449W Abstract During solar cycle 23, 82 interplanetary magnetic clouds (MCs) were identified by the Magnetic Field Investigation (MFI) team using Wind (1995 - 2003) solar wind plasma and magnetic field data from solar minimum through the maximum of cycle 23. The average occurrence rate is 9.5 MCs per year for the overall period. It is found that some of the anomalies in the frequency of occurrence were during the early part of solar cycle 23: (i) only four MCs were observed in 1999, and (ii) an unusually large number of MCs (17 events) were observed in 1997, just after solar minimum. We also discuss the relationship between MCs, coronal mass ejections (CMEs), and geomagnetic storms. During the period 1996 - 2003, almost 8000 CMEs were observed by SOHO-LASCO. The occurrence frequency of MCs appears to be related neither to the occurrence of CMEs as observed by SOHO LASCO nor to the sunspot number. When we included ``magnetic cloud-like structures'' (MCLs, defined by Lepping, Wu, and Berdichevsky, 2005), we found that the occurrence of the joint set (MCs + MCLs) is correlated with both sunspot number and the occurrence rate of CMEs. The average duration of the MCL structures is ~40% shorter than that of the MCs. The MCs are typically more geoeffective than the MCLs, because the average southward field component is generally stronger and longer lasting in MCs than in MCLs. In addition, most severe storms caused by MCs/MCLs with Dst _min<= -100 nT occurred in the active solar period. @-------------------------------------------------------------------- Title: Radio Observatory for Lunar Sortie Science (ROLSS) Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio, L. D.; Lazio, J.; Weiler, K. W.; Bale, S. D.; Burns, J. O.; Jones, D. L.; Kasper, J. C.; Reiner, M. J. Bibliographic Code: 2006AGUFMSM43A1476M Abstract It is widely recognized that the lunar surface is an ideal base for radio astronomy observations at frequencies below the terrestrial ionospheric cutoff frequency. The ionospheric cutoff (10-20 MHz) prevents observations of very low frequency radio sources outside the ionosphere from being conducted by ground-based observatories. Spacecraft or lunar-based observatories are the only alternative, with the lunar surface providing the real estate for establishing radio arrays with large dimensions (tens of kilometers) to perform high resolution imaging at the lowest frequencies (< 10 MHz). In this presentation, we describe a concept study for a pathfinder radio observatory to be deployed during a lunar sortie. The concept study focuses on appropriate antenna, receiver, deployment, power, and communication systems for the observatory. These systems must be low mass to permit the lunar sortie package to maximize science and engineering goals. Power requirements for the receiver systems and the downlink to Earth must also be minimized. The concept study also addresses in detail the science goals of this observatory, which include observations of solar radio bursts as proxies of solar and heliospheric particle acceleration, detailed measurement of the lunar ionosphere scale height as a function of time, integrated spectra of strong (extragalactic) sources to probe particle acceleration processes, and a survey of natural and man-made emissions from the Earth. These observations will enhance our understanding of the various radio sources and the lunar observing environment and pave the way for future larger-scale lunar radio astronomy arrays. @-------------------------------------------------------------------- Title: Investigating the state of the Sun-Earth system during extreme events: First science results of a worldwide online conference series Authors: Kozyra, J. U.; Shibata, K.; Fox, N. J.; Basu, S.; Coster, A. J.; Davila, J. M.; Gopalswamy, N.; Liou, K.; Lu, G.; Mann, I. R.; Pallamraju, D.; Paxton, L. J.; Peterson, W. K.; Talaat, E. R.; Weatherwax, A. T.; Young, C. A.; Zanetti, L. J. Bibliographic Code: 2006AGUFMSA43A..01K Abstract This presentation reports on new science results from an online conference entitled "Return to the Auroral Oval for the Anniversary of the IGY" designed to bring together researchers worldwide: (1) to investigate newly reported features in the auroral oval during substorms that occur in the main phase of superstorms and how these features map throughout geospace, (2) to explore implications for the state of the geospace system, (3) to identify signatures associated with this geospace state from equatorial to polar latitudes, (4) to investigate the unusual aspects of the solar sources, and (5) to understand how propagation from Sun to Earth modified the observed solar drivers. The main focus of the first conference is on worldwide data exchange, the construction of global data products and assimilative global views, and identifying coupled chains of events from sun-to-Earth. The collaborative conference data products and enhanced understanding of the observed features of the events will form the basis for a follow-on conference in 2007 focused primarily on theoretical studies and collaborative simulation efforts between modeling groups, observers and data analysts. This conference is the first in a series of sun-Earth connection online conferences, sponsored by CAWSES, IHY, eGY, ICESTAR, NASA/LWS, and NSF Atmospheric Science Programs, and designed to bring interdisciplinary researchers together with the vast developing cyber-infrastructure of large international data sets, high performance computing and advanced visualizations to address grand challenge science issues in a way not previously possible. @-------------------------------------------------------------------- Title: IHY-CAWSES Data base Authors: Young, C. A.; Thompson, B. J.; Davila, J.; Gopalswamy, N. Bibliographic Code: 2006ihy..workE..90Y Abstract In partnership with the CAWSES (Climate And Weather of the Sun-Earth System) program, IHY is sponsoring a series of Virtual Workshops and a special IHY/CAWSES database to provide virtual access of data collected for IHY and CAWSES campaigns. The first of the virtual workshops occurred November 13-17, 2006, and had more than 200 online participants. Online presentation and discussion tools are being refined for future workshops. The IHY/CAWSES database provides a means of entering data into the Virtual Solar Observatory (to provide the maximum and easiest possible access to the data) while still maintaining a close connection to the other data sets used in IHY/CAWSES activities. @-------------------------------------------------------------------- Title: General Discussion on Donor Programs Authors: Gopalswamy, N. Bibliographic Code: 2006ihy..workE..88G Abstract @-------------------------------------------------------------------- Title: General Discussion on Donor Programs Authors: Gopalswamy, N. Bibliographic Code: 2006ihy..workE..87G Abstract @-------------------------------------------------------------------- Title: General Discussion on Donor Programs N. Gopalswamy Authors: Gopalswamy, N. Bibliographic Code: 2006ihy..workE..86G Abstract @-------------------------------------------------------------------- Title: Coronal Mass Ejections in the Heliosphere Authors: Gopalswamy, N. Bibliographic Code: 2006ihy..workE..46G Abstract Coronal mass ejections (CMEs) are the most energetic events in the heliosphere. They carry large amounts of coronal magnetic fields and plasma with them and driving large-scale interplanetary shocks. The CMEs and shock have significant consequences at various locations in the heliosphere, including the production of intense geomagnetic storms and large energetic particle events. CMEs form merged interaction regions in the heliosphere, which act as magnetic barriers for the galactic cosmic rays entering the heliosphere. After a brief summary of the observed properties of CMEs at the Sun, I discuss the properties of the interplanetary CMEs (ICMEs) and their connection to shocks, radio bursts, solar energetic particles and modulation of galactic cosmic rays. @-------------------------------------------------------------------- Title: IHY/UNBSS Program: Success Stories Authors: Gopalswamy, N.; Davila, J.; Thompson, B. J.; Haubold, H. J. Bibliographic Code: 2006ihy..workE..15G Abstract The United Nations Office for Outer Space Affairs, through the IHY secretariat and the United Nations Basic Space Science Initiative (UNBSSI) is assisting scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of the IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. The small instrument program is a partnership between instrument providers, and instrument hosts in developing countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Existing data bases and relevant software tools can be identified to promote space science activities in developing countries. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides an overview of the IHY/UNBSS program, its achievements and future plans. @-------------------------------------------------------------------- Title: Properties and geoeffectiveness of halo coronal mass ejections Authors: Michalek, G.; Gopalswamy, N.; Lara, A.; Yashiro, S. Bibliographic Code: 2006SpWea...410003M, eprint = 0710.4526 Abstract Halo coronal mass ejections (HCMEs) originating from regions close to the center of the Sun are likely to be geoeffective. Assuming that the shape of HCMEs is a cone and that the HCMEs propagate with constant angular widths and velocities, at least in their early phase, we have developed a technique which allowed us to obtain the space speed, width, and source location. We apply this technique to obtain the parameters of all full HCMEs observed by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) experiment until the end of 2002. Using this data, we examine which parameters determine the geoeffectiveness of HCMEs. We show that in the considered period of time, only fast halo CMEs (with space velocities higher than ~1000 km/s) and originating from the Western Hemisphere close to the solar center could cause intense geomagnetic storms. We illustrate how the HCME parameters can be used for space weather forecast. It is also demonstrated that the strength of a geomagnetic storm does not depend on the determined width of HCMEs. This means that HCMEs do not have to be very large to cause major geomagnetic storms. @-------------------------------------------------------------------- Title: Improved input to the empirical coronal mass ejection (CME) driven shock arrival model from CME cone models Authors: Xie, H.; Gopalswamy, N.; Ofman, L.; St. Cyr, O. C.; Michalek, G.; Lara, A.; Yashiro, S. Bibliographic Code: 2006SpWea...410002X Abstract We study the Sun-Earth travel time of interplanetary shocks driven by coronal mass ejections (CMEs) using empirical cone models. Three different cone models have been used to obtain the radial speeds of the CMEs, which are then used as input to the empirical shock arrival (ESA) model to obtain the Sun to Earth travel time of the shocks. We compare the predicted and observed shock transit times and find that the accuracy of the ESA model is improved by applying CME radial speeds from the cone models. There are two ways of calculating the shock travel time: using the ESA model or using the simplified ESA formula obtained by an exponential fit to the ESA model. The average mean error in the travel time with the cone model speeds is 7.8 hours compared to 14.6 hours with the sky plane speed, which amounts to an improvement of 46%. With the ESA formula, the corresponding mean errors are 9.5 and 11.7 hours, respectively, representing an improvement of 19%. The cone models minimize projection effects and hence can be used to obtain CME radial speeds. When input to the ESA model, the large scatter in the shock travel time is reduced, thus improving CME-related space weather predictions. @-------------------------------------------------------------------- Title: Different Power-Law Indices in the Frequency Distributions of Flares with and without Coronal Mass Ejections Authors: Yashiro, S.; Akiyama, S.; Gopalswamy, N.; Howard, R. A. Bibliographic Code: 2006ApJ...650L.143Y, eprint = astro-ph/0609197 Abstract We investigated the frequency distributions of flares with and without coronal mass ejections (CMEs) as a function of flare parameters (peak flux, fluence, and duration of soft X-ray flares). We used CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission and soft X-ray flares (C3.2 and above) observed by the Geostationary Operational Environmental Satellite (GOES) during 1996-2005. We found that the distributions obey a power law of the form dN/dX~X^-alpha, where X is a flare parameter and dN is the number of events recorded within the interval [X, X+dX]. For the flares with (without) CMEs, we obtained the power-law index alpha=1.98+/-0.05 (alpha=2.52+/-0.03) for the peak flux, alpha=1.79+/-0.05 (alpha=2.47+/-0.11) for the fluence, and alpha=2.49+/-0.11 (alpha=3.22+/-0.15) for the duration. The power-law indices for flares without CMEs are steeper than those for flares with CMEs. The larger power-law index for flares without CMEs supports the possibility that nanoflares contribute to coronal heating. @-------------------------------------------------------------------- Title: Solar Sources of Impulsive Solar Energetic Particle Events and Their Magnetic Field Connection to the Earth Authors: Nitta, Nariaki V.; Reames, Donald V.; De Rosa, Marc L.; Liu, Yang; Yashiro, Seiji; Gopalswamy, Natchimuthuk Bibliographic Code: 2006ApJ...650..438N Abstract This paper investigates the solar origin of impulsive solar energetic particle (SEP) events, often referred to as ³He-rich flares, by attempting to locate the source regions of 117 events as observed at ~2-3 MeV amu^-1. Given large uncertainties as to when ions at these energies were injected, we use type III radio bursts that occur within a 5 hr time window preceding the observed ion onset, and search in EUV and X-ray full-disk images for brightenings around the times of the type III bursts. In this way we find the solar sources in 69 events. High cadence EUV images often reveal a jet in the source region shortly after the type III burst. We also study magnetic field connections between the Earth and the solar sources of impulsive SEP events as identified above, combining the potential field source surface (PFSS) model for the coronal field and the Parker spiral for the interplanetary magnetic field. We find open field lines in and around ~80% of the source regions. But only in ~40% of the cases, can we find field lines that are both close to the source region at the photosphere and to the Parker spiral coordinates at the source surface, suggesting challenges in understanding the Sun-Earth magnetic field with observations available at present and in near future. @-------------------------------------------------------------------- Title: Coronal Mass Ejections of Solar Cycle 23 Authors: Gopalswamy, Nat Bibliographic Code: 2006JApA...27..243G Abstract I summarize the statistical, physical, and morphological properties of coronal mass ejections (CMEs) of solar cycle 23, as observed by the Solar and Heliospheric Observatory (SOHO) mission. The SOHO data is by far the most extensive data, which made it possible to fully establish the properties of CMEs as a phenomenon of utmost importance to Sun-Earth connection as well as to the heliosphere. I also discuss various subsets of CMEs that are of primary importance for their impact on Earth. @-------------------------------------------------------------------- Title: Correction to ``Introduction to special section on corotating solar wind streams and recurrent geomagnetic activity'' Authors: Tsurutani, B. T.; McPherron, R. L.; Gonzalez, W. D.; Lu, G.; Sobral, J. H. A.; Gopalswamy, N. Bibliographic Code: 2006JGRA..11108S90T Abstract Abstract Available from http://www.agu.org @-------------------------------------------------------------------- Title: The United Nations Basic Space Science Initiative for IHY 2007 Authors: Gopalswamy, N.; Davila, J. M.; Thompson, B. J.; Haubold, H. Bibliographic Code: 2006IAUSS...5E..47G Abstract The United Nations, in cooperation with national and international space-related agencies and organizations, has been organizing annual workshops since 1990 on basic space science, particularly for the benefit of scientists and engineers from developing nations. The United Nations Office for Outer Space Affairs, through the IHY Secretariat and the United Nations Basic Space Science Initiative (UNBSSI) will assist scientists and engineers from all over the world in participating in the International Heliophysical Year (IHY) 2007. A major thrust of the IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, all-sky cameras, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. The small instrument program is envisioned as a partnership between instrument providers, and instrument hosts in developing countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Funds are not available through the IHY to build the instruments; these must be obtained through the normal proposal channels. However all instrument operational support for local scientists, facilities, data acquisition, etc will be provided by the host nation. It is our hope that the IHY/UNBSSI program can facilitate the deployment of several of these networks world wide. Existing data bases and relevant software tools that can will be identified to promote space science activities in developing countries. Extensive data on space science have been accumulated by a number of space missions. Similarly, long-term data bases are available from ground based observations. These data can be utilized in ways different from originally intended for understanding the heliophysical processes. This paper provides an overview of the IHY/UNBSS program, its achievements and future plans. @-------------------------------------------------------------------- Title: The IHY Program and Associated IAU Activities Authors: Webb, D.; Gopalswamy, N. Bibliographic Code: 2006IAUSS...5E..43W Abstract The International Heliospheric Year is an international program of scientific collaboration planned for the time period starting next year, the 50th anniversary of the International Geophysical Year. The physical realm of the IHY encompasses all of the solar system out to the interstellar medium, representing a direct connection between in-situ and remote observations. The IHY is of great interest to the IAU because of this broad astronomical coverage as well as its emphasis on international cooperation and developing nations. The IHY program is promoting worldwide participation in its activities that include dispersing networks of inexpensive instrumentation to achieve its scientific goals. Within the IAU the IHY program is organized under Division II, which covers the Sun and Heliosphere. Nat Gopalswamy is the IHY International Coordinator and Chair of the IHY subgroup within the IAU's Working Group on International Collaboration on Space Weather. David Webb is the IAU representative for the IHY and the outgoing President of Division II. The United Nations IHY effort is led by Hans Haubold under the UNBSS program and will be discussed next by Dr. Gopalswamy. Under this program the IAU is supporting the annual IHY Workshops and is facilitating the communications between scientists in developed and developing countries. @-------------------------------------------------------------------- Title: Mission Concepts for Spacecraft and Lunar-based Radio Source Imaging at Frequencies below the Ionospheric Cutoff Authors: Gopalswamy, N.; MacDowall, R. J.; Kaiser, M. L.; Demaio, L. D.; Bale, S. D.; Howard, R. E.; Jones, D. L.; Kasper, J. C.; Kassim, N. E.; Lazio, J. W.; Weiler, K. W.; Reiner, M. J. Bibliographic Code: 2006IAUJD..12E..21G Abstract No present or approved spacecraft mission has the capability to provide high angular resolution imaging of solar or magnetospheric radio bursts or of the celestial sphere at frequencies below the ionospheric cutoff. In this presentation, we review briefly the history of space-based radio observations by single spacecraft. Although these missions did not produce images of discrete radio sources, they did establish important constraints for future imaging missions. Subsequently, we present in detail an active NASA mission proposal to perform such imaging in the frequency range ~30 kHz to 15 MHz. The focus of this mission, the Solar Imaging Radio Array (SIRA), is solar and NASA exploration-oriented, with emphasis on improved understanding and space weather application of radio bursts associated with solar energetic particle (SEP) events and on tracking shocks and other components of coronal mass ejections (CMEs). SIRA will also map the astrophysical sky. SIRA will require a minimum of 12 to 16 micro-satellites to establish a sufficient number of baselines with separations on the order of a kilometer. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, earth pointing high gain antenna. The constellation will likely be placed in an L1 halo orbit, which is the preferred location for full-time solar observations. We will also discuss follow-on missions that would be lunar-based, ultimately with of order 10,000 dipole antennas. The lunar missions would be adaptations of ground-based interferometric arrays like LOFAR, LWA, MWA, etc. Basic research in radio astronomy at the Naval Research Laboratory is supported by the Office of Naval Research; part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. @-------------------------------------------------------------------- Title: Anemone structure of Active Region NOAA 10798 and related geo-effective flares/ CMEs Authors: Asai, A.; Ishii, T. T.; Shibata, K.; Gopalswamy, N. Bibliographic Code: 2006IAUJD...3E..72A Abstract Introduction: We report the evolution and the coronal features of an active region NOAA 10798, and the related magnetic storms. Method: We examined in detail the photospheric and coronal features of the active region by using observational data in soft X-rays, in extreme ultraviolet images, and in magnetogram obtained with GOES, SOHO satellites. We also examined the interplanetary disturbances from the ACE data. Results: This active region was located in the middle of a small coronal hole, and generated 3 M-class flares. The flares are associated with high speed CMEs up to 2000 km/s. The interplanetary disturbances also show a structure with southward strong magnetic field. These produced a magnetic storm on 2005 August 24. Conclusions: The anemone structure may play a role for producing the high-speed and geo-effective CMEs even the near limb locations. @-------------------------------------------------------------------- Title: Solar Energetic Particles and CME-driven Shocks Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Bougeret, J.-L. Bibliographic Code: 2006IAUJD...1E..54G Abstract Large solar energetic particle (SEP) events are associated with coronal mass ejections (CMEs) of very high speed (~1500 km/s). A mass mtion of such high speeds in the coronal and interplanetary plasma has to drive fast mode MHD shocks. Direct evidence of such shocks come from in situ observations of shock arriving at 1 AU immediately followed by the driving CMEs. The energetic storm particle (ESP) events associated with these shocks present direct evidence for shock acceleration. Shocks near the Sun have to be remote-sensed using type II bursts of type II. Type II bursts occurring over wide range of wavelengths are known to be associated with very fast and wide CMEs (Gopalswamy et al., 2005). We analyze a set of such type II bursts observed during solar cycle 23 and the associated SEP and CME events to explore the relationship bewteen CME-driven shocks and SEPs near the Sun. We also study the association of the type II burst events with the interplanetary shocks observed in situ and ESP events. The main result is that when the CME associated with the type II bursts originate on the disk center of the Sun, they result in shocks at 1 AU followed by driving CMEs. We also discuss the relationship bewteen type II bursts and ESP events. Reference: Gopalswamy, N., E. Aguilar-Rodriguez, S. Yashiro, S. Nunes, M. L. Kaiser, and R. A. Howard, Type II radio bursts and energetic solar eruptions, JGRA, 110, 12, 2005 @-------------------------------------------------------------------- Title: On the Rates of Coronal Mass Ejections: Remote Solar and In Situ Observations Authors: Riley, Pete; Schatzman, C.; Cane, H. V.; Richardson, I. G.; Gopalswamy, N. Bibliographic Code: 2006ApJ...647..648R Abstract We compare the rates of coronal mass ejections (CMEs) as inferred from remote solar observations and interplanetary CMEs (ICMEs) as inferred from in situ observations at both 1 AU and Ulysses from 1996 through 2004. We also distinguish between those ICMEs that contain a magnetic cloud (MC) and those that do not. While the rates of CMEs and ICMEs track each other well at solar minimum, they diverge significantly in early 1998, during the ascending phase of the solar cycle, with the remote solar observations yielding approximately 20 times more events than are seen at 1 AU. This divergence persists through 2004. A similar divergence occurs between MCs and non-MC ICMEs. We argue that these divergences are due to the birth of midlatitude active regions, which are the sites of a distinct population of CMEs, only partially intercepted by Earth, and we present a simple geometric argument showing that the CME and ICME rates are consistent with one another. We also acknowledge contributions from (1) an increased rate of high-latitude CMEs and (2) focusing effects from the global solar field. While our analysis, coupled with numerical modeling results, generally supports the interpretation that whether one observes a MC within an ICME is sensitive to the trajectory of the spacecraft through the ICME (i.e., an observational selection effect), one result directly contradicts it. Specifically, we find no systematic offset between the latitudinal origin of ICMEs that contain MCs at 1 AU in the ecliptic plane and that of those that do not. @-------------------------------------------------------------------- Title: Introduction to special section on corotating solar wind streams and recurrent geomagnetic activity Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter D.; Lu, Gang; Sobral, Jose H. A.; Gopalswamy, Nat Bibliographic Code: 2006JGRA..11107S00T Abstract Abstract Available from http://www.agu.org @-------------------------------------------------------------------- Title: Observational Properties of CMEs from a Decade-Long Observations by SOHO Authors: Gopalswamy, N.; Yashiro, S.; Howard, R. A. Bibliographic Code: 2006ESASP.617E.129G Abstract @-------------------------------------------------------------------- Title: Properties of Interplanetary Coronal Mass Ejections Authors: Gopalswamy, Nat Bibliographic Code: 2006SSRv..124..145G Abstract Interplanetary coronal mass ejections (ICMEs) originating from closed field regions on the Sun are the most energetic phenomenon in the heliosphere. They cause intense geomagnetic storms and drive fast mode shocks that accelerate charged particles. ICMEs are the interplanetary manifestations of CMEs typically remote-sensed by coronagraphs. This paper summarizes the observational properties of ICMEs with reference to the ordinary solar wind and the progenitor CMEs. @-------------------------------------------------------------------- Title: Coronal and Interplanetary Type II Bursts Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L. Bibliographic Code: 2006SPD....37.2501G Abstract The kinetic energy of coronal mass ejections (CMEs) has been shown to essentially decide the wavelength range over which type II radio emission occurs. The larger the kinetic energy the wider is the wavelength range over which emission takes place. In other words, CMEs with larger kinetic energy drive shocks farther into the interplanetary medium. We studied a set of about 70 type II bursts that had emission components in the three well-known wavelength domains: metric (m), decameter-hectometric (DH), and kilometric (km). We find that the properties of CMEs associated with the m-to-km type II bursts are nearly identical to those CMEs associated with solar energetic particle events. We suggest that this correlation is evidence for the same shock accelerating electrons and ions. Next we examined the time delay between the onsets of metric and interplanetary type II emission. This is an important parameter because only when a metric type II burst has IP counterpart, it is likely to have space weather consequences. We find that the typical delay is about 1 hour. This is sufficiently small that one can use the DH type II bursts to identify shocks that might impact various destinations in the inner heliosphere. @-------------------------------------------------------------------- Title: Corotating solar wind streams and recurrent geomagnetic activity: A review Authors: Tsurutani, Bruce T.; Gonzalez, Walter D.; Gonzalez, Alicia L. C.; Guarnieri, Fernando L.; Gopalswamy, Nat; Grande, Manuel; Kamide, Yohsuke; Kasahara, Yoshiya; Lu, Gang; Mann, Ian; McPherron, Robert; Soraas, Finn; Vasyliunas, Vytenis Bibliographic Code: 2006JGRA..11107S01T Abstract Solar wind fast streams emanating from solar coronal holes cause recurrent, moderate intensity geomagnetic activity at Earth. Intense magnetic field regions called Corotating Interaction Regions or CIRs are created by the interaction of fast streams with upstream slow streams. Because of the highly oscillatory nature of the GSM magnetic field z component within CIRs, the resultant magnetic storms are typically only weak to moderate in intensity. CIR-generated magnetic storm main phases of intensity Dst < -100 nT (major storms) are rare. The elongated storm ``recovery'' phases which are characterized by continuous AE activity that can last for up to 27 days (a solar rotation) are caused by nonlinear Alfven waves within the high streams proper. Magnetic reconnection associated with the southward (GSM) components of the Alfvén waves is the solar wind energy transfer mechanism. The acceleration of relativistic electrons occurs during these magnetic storm ``recovery'' phases. The magnetic reconnection associated with the Alfvén waves cause continuous, shallow injections of plasma sheet plasma into the magnetosphere. The asymmetric plasma is unstable to wave (chorus and other modes) growth, a feature central to many theories of electron acceleration. It is noted that the continuous AE activity is not a series of substorm expansion phases. Arguments are also presented why these AE activity intervals are not convection bays. The auroras during these continuous AE activity intervals are less intense than substorm auroras and are global (both dayside and nightside) in nature. Owing to the continuous nature of this activity, it is possible that there is greater average energy input into the magnetosphere/ionosphere system during far declining phases of the solar cycle compared with those during solar maximum. The discontinuities and magnetic decreases (MDs) associated with interplanetary Alfven waves may be important for geomagnetic activity. In conclusion, it will be shown that geomagnetic storms associated with high-speed streams/CIRs will have the same initial, main, and ``recovery'' phases as those associated with ICME-related magnetic storms but that the interplanetary causes are considerably different. @-------------------------------------------------------------------- Title: Are halo coronal mass ejections special events? Authors: Lara, Alejandro; Gopalswamy, Nat; Xie, Hong; Mendoza-Torres, Eduardo; Pérez-Eríquez, Román; Michalek, Gregory Bibliographic Code: 2006JGRA..11106107L Abstract We revisited the properties of wide coronal mass ejections (CMEs) called halo CMEs. Using the large LASCO/SOHO CMEs data set, from 1996 to 2004, we examined the statistical properties of (partial and full) halo CMEs and compare with the same properties of ``normal'' width (lower than 120°) CMEs. We found that halo CMEs have different properties than ``normal'' CMEs, which cannot be explained merely by the current geometric interpretation that they are seen as halos because they are traveling in the Sun Earth direction. We found that the CME width distribution is formed by, at least, three different populations: Two gaussians: a narrow and a medium distribution centered at ~17° and ~38°, respectively; the narrow population most likely corresponds to the ``true'' observed widths, whereas the medium width population is the product of projection effects. The third distribution corresponds to wider CMEs (80° < W < 210°) which behaves as a power law. Partial and full halo CMEs wider than these do not follow any particular distribution. This lack of regularity may be due to the small number of such events. In particular, we found (and test by a statistical approach) that the number of observed full halo CMEs is lower than expected. The CME speed follows a log-normal distribution, except for the very low speed CME population, which follows a gaussian distribution centered at ~100 km/s and is probably due to projection effects. When the CMEs are divided by width into nonhalo, partial halo, and full halo, we found that the peaks of the distributions are shifted toward higher speeds, ~300, ~400 and ~600 km/s for nonhalo, partial halo, and full halo CMEs, respectively. This confirms that halo CMEs tend to be high speed CMEs. The acceleration of full halo CMEs tends to be more negative compared with nonhalo and partial halo CMEs. We introduce a new observational CME parameter: The final observed distance (FOD), i.e., the highest point within the coronograph field of view where a CME can be distinguished from the background. In other words, the highest CME altitude measured. The FOD for nonhalo CMEs decreases exponentially from ~5 to ~30 R_$\odot$ in the LASCO field of view. On the other hand, the FOD of halo CMEs increase with distance. This means that it is more likely to see halo CMEs at large distances (from the Sun) than nonhalo CMEs. These halo CME properties may be explained if the white light wide enhancements (or halo) seen by coronographs correspond to a combination of an expanding (shock) wave which disturbs and/or compresses the ambient material and the CME material itself. @-------------------------------------------------------------------- Title: Preface Authors: Gopalswamy, Nat Bibliographic Code: 2006JApA...27...57G Abstract @-------------------------------------------------------------------- Title: Comment on ``Interplanetary shocks unconnected with earthbound coronal mass ejections'' by T. A. Howard and S. J. Tappin Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Kasper, J. Bibliographic Code: 2006GeoRL..3311108G Abstract Abstract Available from http://www.agu.org @-------------------------------------------------------------------- Title: A Sun-to-Earth Campaign Joining Observations from the Great Observatory with Worldwide Satellite and Ground-Based Resources to Investigate System Science Frontiers Authors: Kozyra, J. U.; Shibata, K.; Barnes, R. J.; Basu, S.; Davila, J. M.; Fox, N. J.; Gopalswamy, N.; Kuznetsova, M. M.; Pallamraju, D.; Paxton, L. J.; Ridley, A.; Weiss, M.; Young, C. A.; Zanetti, L. J. Bibliographic Code: 2006AGUSMSM23A..03K Abstract An Internet-based cross-disciplinary analysis campaign that will make heavy use of Great Observatory missions as well as international satellite and ground-based assets is being undertaken with joint support from the CAWSES, IHY, LWS, and ICESTAR programs planned for late April or early May 2006. An evolving list of open science questions that serve as sun-to-Earth focus areas for the worldwide campaign were identified during a small interdisciplinary CAWSES workshop at Stanford University in December 2005 as well as during a joint CAWSES/ICESTAR session at the CEDAR meeting in Boulder the preceding summer. The analysis campaign will take place over the Internet in the form of virtual poster sessions with message boards and monitors that summarize the important science issues and new results daily. Poster authors will be asked to closely monitor their message boards during the day of their poster session as well as the following day. Outreach to other disciplines and international students will take the form of tutorial talks that place campaign science issues into the context of the current state of knowledge in each discipline area. Global models and data sets (TEC, magnetometer maps, ULF wave maps, assimilative models, MHD model outputs, continuous solar images) will be available to provide context for local and regional observations. The Community Coordinated Data Center (CCMC) is developing a small number of new data display formats that extract data from global models and place it in the same format as the observations either for ground-based stations or along satellite tracks. Other ideas being explored include real time upload of additional posters in response to issues raised during the poster session, library of related articles, reference archive of observations, etc. A summary of which aspects and/or tools worked and which were less useful will be presented. @-------------------------------------------------------------------- Title: Solar Imaging Radio Array: Space-based Radio Imaging at Frequencies Below the Ionospheric Cutoff Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio, L. D.; Bale, S. D.; Kasper, J. C.; Lazarus, A. J.; Howard, R. E.; Jones, D. L.; Reiner, M. J.; Weiler, K. W. Bibliographic Code: 2006AGUSMSH33A..11M Abstract No present or approved spacecraft mission has the capability to provide high angular resolution imaging of solar or magnetospheric radio bursts or of the celestial sphere at frequencies below the ionospheric cutoff. In this presentation, we review a NASA MIDEX-class mission to perform such imaging in the frequency range 30 kHz to 15 MHz. The focus of the mission, the Solar Imaging Radio Array (SIRA), is solar and exploration- oriented, with emphasis on improved understanding and application of radio bursts associated with solar energetic particle (SEP) events and on tracking shocks and other components of coronal mass ejections (CMEs). The data stream will also permit high angular resolution mapping of the celestial sphere at frequencies below 15 MHz, permitting detection of numerous astrophysical objects and extension of their observed spectra to much lower frequencies. SIRA will require 12 to 16 micro-satellites to establish a sufficient number of baselines with separations on the order of kilometers. The constellation consists of microsats located quasi-randomly on a spherical shell, initially of radius 5 km. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, Earth-pointing high gain antenna. The constellation will likely be placed at L1, which is the preferred location for full-time solar observations. Detailed mission science and technology goals will be reviewed. @-------------------------------------------------------------------- Title: Radio manifestation of the interaction between ultra-fast CMEs Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibliographic Code: 2006AGUSMSH24A..03G Abstract Active region 720 was one of the super active regions of cycle 23 in that it produced large numbers of coronal mass ejections (CMEs) and major flares. The average recurrence time between flares in the region was about 2.5 h, but several flares and CMEs occurred with much shorter recurrence time. In this paper, we are concerned with two ultra-fast CMEs (speed > 2000 km/s) originating within 45 minutes. The CMEs merged with each other within the field of view of SOHO coronagraphs. Both CMEs were associated with long wavelength type II radio bursts. The type II burst associated with the first CME was normal, while that associated with the second CME showed irregular spectral behavior, including a characteristic broadband enhancement. Solar energetic particles (SEPs) associated with the two CMEs also showed some peculiarities, which are consistent with the interaction between the two CMEs. The SEP intensity reached a very high value around the time of interaction. We present radio and white light observations of the CMEs and provide an interpretation of the observed spectral features in the radio dynamic spectrum. Work supported by NASA's LWS TR&T and SR&T programs. @-------------------------------------------------------------------- Title: On the rates of coronal mass ejections: remote solar and in situ observations Authors: Riley, P.; Cane, H.; Richardson, I. G.; Gopalswamy, N.; Linker, J. A.; Mikic, Z.; Lionello, R. Bibliographic Code: 2006AGUSMSA21A..01R Abstract In this study we compare the rates of coronal mass ejections (CMEs) as inferred from remote solar observations and interplanetary CMEs (ICMEs) as inferred from in situ observations at both 1 AU and Ulysses for almost an entire solar cycle (1996 through 2004). We find that, while the rates of CMEs and ICMEs track each other well at solar minimum, they diverge significantly in early 1998, during the ascending phase of the solar cycle, with the remote solar observations yielding approximately 20 times more events than are seen in situ at 1 AU. This divergence persists through 2004. We discuss several possible causes, including: (1) the appearance of mid-latitude active regions; (2) the increased rate of high-latitude CMEs; and (3) the strength of the global solar field. We conclude that the most likely interpretation is that this divergence is due to the birth of mid-latitude active regions, which are the sites of a distinct population of CMEs that are only partially intercepted by Earth. This conclusion is supported by the following points: (1) A similar divergence occurs between ICMEs in which magnetic clouds are observed (MCs), and those that are not; and (2) a number of pronounced enhancements in the CME rate, separated by approximately one year, are also mirrored and in ICME rate, but not obviously in the MC rate. We provide a simple geometric argument that shows that the computed CME and ICME rates are consistent with each other. The origins of the individual peaks can be traced back to unusually strong active regions on the Sun. Taken together, these results suggest that whether one observes a flux rope within an ICME is sensitive to the trajectory of the spacecraft through the ICME, i.e., an observational selection effect. This conclusion is supported by models of CME eruption and evolution, which: (1) are incapable of producing a CME that does not contain an embedded flux rope; and (2) demonstrate that glancing intercepts can produce ICME-like signatures without the magnetic structures associated with a flux rope @-------------------------------------------------------------------- Title: Science Plans for the International Heliophysical Year Authors: Davila, J. M.; Gopalswamy, N.; Harrison, R. A.; Stamper, R.; Briand, C.; Potgieter, M. S. Bibliographic Code: 2006AGUSM.U34A..04D Abstract On October 4, 1957, only 53 years after the beginning of flight in Kitty Hawk, the launch of Sputnik 1 marked the beginning of the space age; as mankind took the first steps to leaving the protected environment of Earth's atmosphere. Discovery of the radiation belts, the solar wind, and the structure of Earth's magnetosphere prepared the way for the inevitable human exploration to follow. Soon, Cosmonauts and Astronauts orbited Earth, and then in 1969, Astronauts landed on the Moon. Today a similar story is unfolding, the spacecraft Voyager has crossed the termination shock, and will soon leave the heliosphere. For the first time, man will begin to explore the local interstellar medium. It is inevitable that, during the next 50 years, exploration of the solar system including the Moon, Mars and the outer planets will be the focus of the space program, and like 50 years ago, unmanned probes will lead the way, followed by human exploration. The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, Sun-Earth Connection, planetary science and the heliosphere in general. Now, 50 years later, we have the unique opportunity to further advance our knowledge of the global heliosphere and its interaction with the interstellar medium through the International Heliophysical Year (IHY) in 2007, and to raise public awareness of space physics. This presentation will focus on global science planning efforts and campaigns for all participating IHY nations. @-------------------------------------------------------------------- Title: United Nations Basic Space Science Initiative Programme for the International Heliophysical Year 2007 Authors: Gopalswamy, Nat Bibliographic Code: 2006UNPSA..17...47G Abstract @-------------------------------------------------------------------- Title: Planning the International Heliophysical Year (IHY) Authors: Davila, Joseph M.; Thompson, Barbara J.; Gopalswamy, Nat Bibliographic Code: 2006UNPSA..17...37D Abstract @-------------------------------------------------------------------- Title: The Pre-CME Sun Authors: Gopalswamy, N.; Mikic, Z.; Maia, D.; Alexander, D.; Cremades, H.; Kaufmann, P.; Tripathi, D.; Wang, Y.-M. Bibliographic Code: 2006SSRv..123..303G Abstract The coronal mass ejection (CME) phenomenon occurs in closed magnetic field regions on the Sun such as active regions, filament regions, transequatorial interconnection regions, and complexes involving a combination of these. This chapter describes the current knowledge on these closed field structures and how they lead to CMEs. After describing the specific magnetic structures observed in the CME source region, we compare the substructures of CMEs to what is observed before eruption. Evolution of the closed magnetic structures in response to various photospheric motions over different time scales (convection, differential rotation, meridional circulation) somehow leads to the eruption. We describe this pre-eruption evolution and attempt to link them to the observed features of CMEs. Small-scale energetic signatures in the form of electron acceleration (signified by nonthermal radio bursts at metric wavelengths) and plasma heating (observed as compact soft X-ray brightening) may be indicative of impending CMEs. We survey these pre-eruptive energy releases using observations taken before and during the eruption of several CMEs. Finally, we discuss how the observations can be converted into useful inputs to numerical models that can describe the CME initiation. @-------------------------------------------------------------------- Title: Coronal Observations of CMEs. Report of Working Group A Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.; Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.; Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.; Tripathi, D.; Vourlidas, A.; Wang, Y.-M.; Zhang, J. Bibliographic Code: 2006SSRv..123..127S Abstract CMEs have been observed for over 30 years with a wide variety of instruments. It is now possible to derive detailed and quantitative information on CME morphology, velocity, acceleration and mass. Flares associated with CMEs are observed in X-rays, and several different radio signatures are also seen. Optical and UV spectra of CMEs both on the disk and at the limb provide velocities along the line of sight and diagnostics for temperature, density and composition. From the vast quantity of data we attempt to synthesize the current state of knowledge of the properties of CMEs, along with some specific observed characteristics that illuminate the physical processes occurring during CME eruption. These include the common three-part structures of CMEs, which is generally attributed to compressed material at the leading edge, a low-density magnetic bubble and dense prominence gas. Signatures of shock waves are seen, but the location of these shocks relative to the other structures and the occurrence rate at the heights where Solar Energetic Particles are produced remains controversial. The relationships among CMEs, Moreton waves, EIT waves, and EUV dimming are also cloudy. The close connection between CMEs and flares suggests that magnetic reconnection plays an important role in CME eruption and evolution. We discuss the evidence for reconnection in current sheets from white-light, X-ray, radio and UV observations. Finally, we summarize the requirements for future instrumentation that might answer the outstanding questions and the opportunities that new space-based and ground-based observatories will provide in the future. @-------------------------------------------------------------------- Title: Solar wind speed within 20 R_S of the Sun estimated from limb coronal mass ejections Authors: Nakagawa, Tomoko; Gopalswamy, Nat; Yashiro, Seiji Bibliographic Code: 2006JGRA..11101108N Abstract An estimation of the solar wind speed in the vicinity of the Sun is carried out using the initial speed and acceleration of coronal mass ejections (CMEs) that appeared close to the solar limb. A linear relationship was found between the initial acceleration and the speed of the limb CMEs. It appears that a dragging force is acting on the CMEs, depending on the speed difference between the CMEs and the ambient plasma. The ambient solar wind speed within 20 solar radii estimated from low-latitude CMEs during 1998-2003 ranged from 100 to 700 km s^-1, while the solar wind speed measured at 1 AU ranged from 300 to 700 km s^-1. The estimated solar wind speeds in the vicinity of the Sun sometimes agreed with the simultaneous in situ measurements at 1 AU, but in other periods they were slower than the speeds measured at 1 AU. It is suggested that most of the time the low-latitude solar wind completes accelerating within 20 solar radii, but occasionally additional acceleration is present beyond 20 solar radii. @-------------------------------------------------------------------- Title: Long-lived geomagnetic storms and coronal mass ejections Authors: Xie, H.; Gopalswamy, N.; Manoharan, P. K.; Lara, A.; Yashiro, S.; Lepri, S. Bibliographic Code: 2006JGRA..11101103X Abstract Coronal mass ejections (CMEs) are major solar events that are known to cause large geomagnetic storms (Dst < -100 nT). Isolated geomagnetic storms typically have a main phase of 3-12 hours and a recovery phase of around 1 day. However, there are some storms with main and recovery phases exceeding ~3 days. We trace the origin of these long-lived geomagnetic storms (LLGMS) to frontside halo CMEs. We studied 37 LLGMS events with Dst < -100 nT and the associated CMEs which occurred during 1998-2002. It is found that LLGMS events are caused by (1) successive CMEs, accounting for ~64.9% (24 of 37); (2) single CMEs, accounting for ~21.6% (8 of 37); and (3) high-speed streams (HSS) in corotating interaction regions (CIRs) with no related CME, accounting for ~13.5% (5 of 37). The long duration of the LLGMS events was found to be due to successive CMEs and HSS events; the high intensity of the LLGMS events was related to the interaction of CMEs with other CMEs and HSS events. We find that the duration of LLGMS is well correlated to the number of participating CMEs (correlation coefficient r = 0.78). We also find that the intensity of LLGMS has a good correlation with the degree of interaction (the number of CMEs interacting with a HSS event or with themselves) (r = 0.67). The role of preconditioning in LLGMS events, where the Dst development occurred in multiple steps in the main and recovery phases, has been investigated. It is found that preconditioning does not affect the main phase of the LLGMS events, while it plays an important role during the recovery phase of the LLGMS events. @-------------------------------------------------------------------- Title: Preparing for the International Heliophysical Year (IHY) 2007 Authors: Davila, J. M.; Gopalswamy, N.; Thompson, B. J. Bibliographic Code: 2006ilws.conf..231D Abstract The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, Sun-Earth Connection, planetary science and the heliosphere in general. Now, 50 years later, we have the unique opportunity to advance our knowledge of the global heliosphere and its interaction with planetary bodies and the interstellar medium through the International Heliophysical Year (IHY) in 2007. This will be an international effort, which will raise public awareness of space physics. @-------------------------------------------------------------------- Title: Coronal mass ejections and space weather due to extreme events Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibliographic Code: 2006ilws.conf...79G Abstract This paper summarizes the extreme solar activity and its space weather implications during the declining phase of the solar cycle 23: October-November 2003 (AR 486), November 2004 (AR 696), January 2005 (AR 720), and September 2005 (AR 808). We have compiled and compared the properties of eruptions and the underlying active regions. All these are super active regions, but the flare and CME productivity varied significantly. While the CMEs from all the regions kept the level of solar energetic particles (SEPs) at storm level for several days, their geoeffectiveness (the ability to produce geomagnetic storms) was significantly different, probably due to the location of the eruptions on the Sun. @-------------------------------------------------------------------- Title: Coronal mass ejections and space weather Authors: Webb, D. F.; Gopalswamy, N. Bibliographic Code: 2006ilws.conf...71W Abstract Coronal mass ejections (CMEs) are a key feature of coronal and interplanetary (IP) dynamics. Major CMEs inject large amounts of mass and magnetic fields into the heliosphere and, when aimed Earthward, can cause major geomagnetic storms and drive IP shocks, a key source of solar energetic particles. Studies over this solar cycle using the excellent data sets from the SOHO, TRACE, Yohkoh, Wind, ACE and other spacecraft and ground-based instruments have improved our knowledge of the origins and early development of CMEs at the Sun and how they affect space weather at Earth. A new heliospheric experiment, the Solar Mass Ejection Imager, has completed 3 years in orbit and has obtained results on the propagation of CMEs through the inner heliosphere and their geoeffectiveness. We review key coronal properties of CMEs, their source regions, their manifestations in the solar wind, and their geoeffectiveness. Halo-like CMEs are of special interest for space weather because they suggest the launch of a geoeffective disturbance toward Earth. However, not all halo CMEs are equally geoeffective and this relationship varies over the solar cycle. Although CMEs are involved with the largest storms at all phases of the cycle, recurrent features such as interaction regions and high speed wind streams can also be geoeffective. @-------------------------------------------------------------------- Title: Solar Influence on the Heliosphere and Earth's Environment: Recent Progress and Prospects Authors: Gopalswamy, N.; Bhattacharyya, A. Bibliographic Code: 2006ilws.conf.....G Abstract @-------------------------------------------------------------------- Title: Preface Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter D.; Lu, Gang; Sobral, José Humberto A.; Gopalswamy, Nat Bibliographic Code: 2006GMS...167D...1T Abstract @-------------------------------------------------------------------- Title: Magnetic Storms Caused by Corotating Solar Wind Streams Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter D.; Lu, Gang; Gopalswamy, Nat; Guarnieri, Fernando L. Bibliographic Code: 2006GMS...167....1T Abstract @-------------------------------------------------------------------- Title: Preface Authors: Gopalswamy, Natchimuthukonar; Mewaldt, Richard; Torsti, Jarmo Bibliographic Code: 2006GMS...165D...9G Abstract @-------------------------------------------------------------------- Title: Coronal Mass Ejections and Type II Radio Bursts Authors: Gopalswamy, Nat Bibliographic Code: 2006GMS...165..207G Abstract @-------------------------------------------------------------------- Title: Solar Eruptions and Energetic Particles: An Introduction Authors: Gopalswamy, N.; Mewaldt, R.; Torsti, J. Bibliographic Code: 2006GMS...165....1G Abstract @-------------------------------------------------------------------- Title: The IHY/United Nations Distributed Observatory Development Program Authors: Haubold, H.; Thompson, B. J.; Al-Naimiy, H.; Davila, J. M.; Gopalswamy, N.; Groves, K.; Scherrer, D. Bibliographic Code: 2006cosp...36.3304H Abstract A major thrust of the International Heliophysical Year IHY is to deploy arrays of small inexpensive instruments such as magnetometers radio antennas GPS receivers all-sky cameras etc around the world to provide global measurements of ionospheric magnetospheric and heliospheric phenomena This program is a collaboration between the IHY and the United Nations Basic Space Science Initiative UNBSSI which has been dedicated to the IHY through 2009 The small instrument program consists of a partnership between instrument providers and instrument host countries The lead scientist provides the instrumentation or fabrication plans for instruments in the array the host country provides manpower facilities and operational support to obtain data with the instrument typically at a local university This program has been active in deploying instrumentation developing plans for new instrumentation and identifying educational opportunities for the host nations in association with this program We will discuss the program s status significant deployment activities and plans for 2007-2009 @-------------------------------------------------------------------- Title: International coordinated efforts for IHY 2007 Authors: Gopalswamy, N.; Davila, J.; Thompson, B. Bibliographic Code: 2006cosp...36.2743G Abstract The International Heliophysical Year IHY in 2007 marks the enormous progress made since the International Geophysical Year IGY in 1957 The philosophy behind IHY is similar to that of IGY in studying the environment of our habitat except that the scope has increased to the physical space extending to the interstellar medium This paper describes the international organization of the IHY and planning for a successful program in 2007 In particular we describe the national regional and global efforts in pooling the resources to address the universal processes that govern the solar system and its interaction with the surrounding medium The efforts include identifying science questions of immediate concern and the data sets needed to address these questions The data will be acquired using a truly distributed observatory consisting of all the ground and space-based instruments that exist today and those to be constructed before 2007 The international planning also involves coordinating with the United Nations which through its Basic Space Science Initiative is facilitating the participation of the developing nations in the IHY program An update of the current status of the planning activities at the international level will be presented @-------------------------------------------------------------------- Title: Geoeffectiveness of CMEs: A simple analysis using halo CMEs from SOHO Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S. Bibliographic Code: 2006cosp...36.2723G Abstract We considered the geoeffectiveness of a set of all halo coronal mass Ejections CMEs detected by the Solar and Heliospheric Observatory SOHO during 1996-2003 inclusive Since CMEs take 1-4 days to reach Earth we chose the minimum Dst value over an interval of 1-5 days after the onset of a halo CME Distributions of these Dst values were compared for the following subsets of halo CMEs 1 front-side halos whose solar sources were within 45 degrees from the central meridian 2 Asymmetric halos or limb halos whose sources are front-sided but located beyond 45 degrees from the central meridian and 3 backside halo CMEs We find that the average and median Dst values following the front-side halos are at the intense storm level -100 nT those following the asymmetric halos are at weak storm level -60 nT and those following the backside halos are not indicative of storms Note that we did not eliminate moderate storms caused by high speed streams from coronal holes When we compiled the minimum Dst values during 1-5 days following a set of random days we found that the Dst distribution is nearly identical to the case of backside halos This simple analysis clearly demonstrates that the front-side halos are highly geoeffective whereas the asymmetric halos are marginally geoeffective The backside halo CMEs are not geoeffective at all because the CME plasma is unlikely to reach Earth from backside CMEs @-------------------------------------------------------------------- Title: Anemone structure of AR NOAA 10798 and related geo-effective flares and CMEs Authors: Asai, A.; Ishii, T. T.; Shibata, K.; Gopalswamy, N. Bibliographic Code: 2006cosp...36.2406A Abstract We report coronal features of an active region NOAA 10798 This active region was located in the middle of a small coronal hole and generated 3 M-class flares The flares are associated with high speed CMEs which produced a magnetic storm on 2005 August 24 We examined the coronal features by using observational data in soft X-rays in extreme ultraviolets and in microwaves obtained with GOES SOHO TRACE satellites and Nobeyama Radioheliograph @-------------------------------------------------------------------- Title: Associations of Coronal Mass Ejections as a function of X-ray Flare Properties Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Howard, R. A. Bibliographic Code: 2006cosp...36.1778Y Abstract We examined the associations between coronal mass ejections CMEs and X-ray flares using data from the Large Angle Spectrometric Coronagraph LASCO on board the Solar and Heliospheric Observatory SOHO The CME association of 1540 X-ray flares M classand above detected by GOES satellite were examined As reported in previous studies the CME association rate clearly increased with the peak X-ray intensity the total X-ray intensity and the decay time The CME association rate increased from 40 flare size between M1 0 and M1 7 to 98 flare size above X1 8 Except for an X3 6 flare on July 16 2004 all the 50 huge flares above X1 8 definitely have associated CMEs Furthermore all the X-ray flares with a decay time exceeding 90 min were associated CMEs We discuss which X-ray parameters are essential in order to have CME association @-------------------------------------------------------------------- Title: The CME-productivity associated with flares from two ARs Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2006cosp...36..556A Abstract NOAA active region AR 10039 appeared at the east limb on 21 July 2002 and rotated out of the earthside on 4 August This AR was magnetically complex consisting of a spot group with a beta-gamma delta BGD configuration from the start It produced 3 X- and 8 M-Class X-ray flares during its disk passage NOAA AR 10044 located just to the southwest of AR 10039 developed gradually into a BGD configuration on 26 July and produced 9 M-class flares We examined the coronal mass ejection CME associations rate R of these X-ray flares using data from the Large Angle Spectrometric Coronagraph LASCO on board the Solar and Heliospheric Observatory SOHO We found the CME-productivity to be different between the two ARs AR 10039 was CME-rich with 72 association with flares while AR 10044 was CME-poor with an association rate of only 13 We also calculated the average velocity and angular width of CMEs from the two ARs On the average the CMEs from the CME-rich AR were faster 1195 km s and wider 246 deg than the ones from the CME-poor AR 282 km s and 12 deg We discuss the characteristics of the ARs which might have resulted in the observed differences @-------------------------------------------------------------------- Title: The Pre-CME Sun Authors: Gopalswamy, N.; Mikic, Z.; Maia, D.; Alexander, D.; Cremades, H.; Kaufmann, P.; Tripathi, D.; Wang, Y.-M. Bibliographic Code: 2006cme..book..303G Abstract The coronal mass ejection (CME) phenomenon occurs in closed magnetic field regions on the Sun such as active regions, filament regions, transequatorial interconnection regions, and complexes involving a combination of these. This chapter describes the current knowledge on these closed field structures and how they lead to CMEs. After describing the specific magnetic structures observed in the CME source region, we compare the substructures of CMEs to what is observed before eruption. Evolution of the closed magnetic structures in response to various photospheric motions over different time scales (convection, differential rotation, meridional circulation) somehow leads to the eruption. We describe this pre-eruption evolution and attempt to link them to the observed features of CMEs. Small-scale energetic signatures in the form of electron acceleration (signified by nonthermal radio bursts at metric wavelengths) and plasma heating (observed as compact soft X-ray brightening) may be indicative of impending CMEs. We survey these pre-eruptive energy releases using observations taken before and during the eruption of several CMEs. Finally, we discuss how the observations can be converted into useful inputs to numerical models that can describe the CME initiation. @-------------------------------------------------------------------- Title: Coronal Observations of CMEs Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.; Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.; Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.; Tripathi, D.; Vourlidas, A.; Wang, Y.-M.; Zhang, J. Bibliographic Code: 2006cme..book..127S Abstract CMEs have been observed for over 30 years with a wide variety of instruments. It is now possible to derive detailed and quantitative information on CME morphology, velocity, acceleration and mass. Flares associated with CMEs are observed in X-rays, and several different radio signatures are also seen. Optical and UV spectra of CMEs both on the disk and at the limb provide velocities along the line of sight and diagnostics for temperature, density and composition. From the vast quantity of data we attempt to synthesize the current state of knowledge of the properties of CMEs, along with some specific observed characteristics that illuminate the physical processes occurring during CME eruption. These include the common three-part structures of CMEs, which is generally attributed to compressed material at the leading edge, a low-density magnetic bubble and dense prominence gas. Signatures of shock waves are seen, but the location of these shocks relative to the other structures and the occurrence rate at the heights where Solar Energetic Particles are produced remains controversial. The relationships among CMEs, Moreton waves, EIT waves, and EUV dimming are also cloudy. The close connection between CMEs and flares suggests that magnetic reconnection plays an important role in CME eruption and evolution. We discuss the evidence for reconnection in current sheets from white-light, X-ray, radio and UV observations. Finally, we summarize the requirements for future instrumentation that might answer the outstanding questions and the opportunities that new space-based and ground-based observatories will provide in the future. @-------------------------------------------------------------------- Title: The International Heliophysical Year (IHY) 2007 Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N. Bibliographic Code: 2006AfrSk..10....4D Abstract The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, the Sun-Earth connection, planetary science, and the heliosphere in general. Now, fifty years later, we have the unique opportunity to advance our knowledge of the global heliosphere and its interaction with planetary bodies and the interstellar medium through the International Heliophysical Year (IHY) in 2007. This will be an international effort which will raise public awareness of space physics. Because of its unique geographic position, Africa is well-positioned to play a critical role. @-------------------------------------------------------------------- Title: Composition and magnetic structure of interplanetary coronal mass ejections at 1 AU Authors: Aguilar-Rodriguez, E.; Blanco-Cano, X.; Gopalswamy, N. Bibliographic Code: 2006AdSpR..38..522A Abstract We study the magnetic structure and charge state ratio of interplanetary coronal mass ejections (ICMEs) observed by ACE and Wind spacecraft. Measurements of abundances and charge state ratio of heavy ions (e.g. O⁷⁺/O⁶⁺, C⁶⁺/C⁵⁺, and Mg¹⁰⁺/O⁶⁺) in the plasma as well as magnetic field structure are important tracers for physical conditions and processes in the source regions of ICMEs. We used ion composition (from ACE), plasma (from Wind) and magnetic field (from Wind and ACE) data from 1998 to 2002. Using the low proton temperature criterion, a common plasma signature of ICMEs, we identified 154 events which include magnetic clouds, non-cloud ejecta and complex ICMEs. The latter one refers to compound events resulting from the overtaking of successive ICMEs which can include both magnetic clouds and non-cloud ejecta. We find that there is a close relationship between the increase in the charge state ionization factor and the magnetic structure of ICMEs. Events with magnetic cloud topology show higher QandQ charge state ratios than those with non-magnetic cloud structure. However, both magnetic cloud and non-cloud events show an increase in these ratios when compared with the ambient solar wind. In contrast, perhaps due to instrumental effects, the charge state ratio Q for all events does not show a real enhancement when compared with the ambient solar wind. The difference in ionization states between non-cloud ejecta and magnetic clouds is more pronounced in fast solar wind than when events are embedded in slow wind. @-------------------------------------------------------------------- Title: Introduction to special section on Solar Coronal Mass Ejections and Energetic Particles Authors: Gopalswamy, Nat; Torsti, J. Bibliographic Code: 2005JGRA..11012S00G Abstract Abstract Available from http://www.agu.org @-------------------------------------------------------------------- Title: Workshop Highlights Progress in Solar-Heliospheric Physics Authors: Gopalswamy, Nat Bibliographic Code: 2005EOSTr..86..525G Abstract The Solar, Heliospheric, and Interplanetary Environment (SHINE) group is an affiliation of researchers dedicated to promoting an enhanced understanding of the processes by which magnetic fields, plasmas, and energetic particles are produced near the Sun and propagated through the interplanetary medium to Earth and other locations in the heliosphere. The group conducted its annual workshop in July to discuss recent developments in the study of solar variability and its impact on Earth's space environment. One hundred fifty-five scientists, including 27 students, participated in the plenary, working group, and poster sessions. Student Day activities on 10 July consisted of tutorials given by experienced scientists: solar flares and particle acceleration (Robert Lin, University of California Berkeley), the origin of coronal mass ejections (CMEs) (Spiro Antiochos, Naval Research Laboratory, Washington, D.C.), connecting the Sun and heliosphere (Thomas Zurbuchen, University of Michigan, Ann Arbor), and acceleration and transport of solar energetic particles (SEPs) (Christina Cohen, California Institute of Technology, Pasadena). The tutorials were followed by student presentations on CMEs near the sun and in the interplanetary medium, solar wind, and SEPs. @-------------------------------------------------------------------- Title: The Solar Imaging Radio Array: Space-Based Imaging of Solar, Heliospheric, Magnetospheric, and Astrophysical Sources at Frequencies below the Ionospheric Cutoff Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Bale, S. D.; Demaio, L. D.; Hewitt, J. N.; Kasper, J. C.; Lazarus, A. J.; Howard, R. E.; Jones, D. L.; Reiner, M. J.; Weiler, K. W. Bibliographic Code: 2005ASPC..345..476M Abstract Solar Imaging Radio Array (SIRA) is a mission concept for space-based, interferometric imaging of solar and interplanetary radio emission at frequencies below the Earth's ionospheric cutoff. Observing in a frequency range of ˜30 kHz to 15 MHz, SIRA will observe the radio emission from shocks driven by fast coronal mass ejections (CMEs). The radio emissions permit tracking the leading boundaries of CMEs from ˜2 R_s to 1 AU. When a CME impacts Earth's magnetosphere, the dynamic response will be imaged in the light of magnetospheric radio emissions, such as auroral kilometric radiation (AKR), scattered on magnetospheric density gradients. The near-term possibility for a SIRA mission is based on a NASA MIDEX-class mission, consisting of a single constellation of ˜16 microsats located quasi-randomly on a spherical shell of ˜10 km diameter. Such a mission is the logical next step in space-based solar radio observations, as well as offering a unique space weather prediction capability for the NASA Exploration Initiative. SIRA will also serve a valuable role as a pathfinder for more complex constellation and interferometry missions. @-------------------------------------------------------------------- Title: Distributed Instrumentation Deployment During the IHY Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N. Bibliographic Code: 2005AGUFMSM21A0347D Abstract A major thrust of the International Heliophysical Year (IHY) is to deploy arrays of small, inexpensive instruments such as magnetometers, radio antennas, GPS receivers, all-sky cameras, etc. around the world to provide global measurements of ionospheric and heliospheric phenomena. This program is a collaboration between the IHY and the United Nations Basic Space Science (UNBSS) program, which has been dedicated to the IHY through 2009. The small instrument program is envisioned as a partnership between instrument providers, and instrument host countries. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument typically at a local university. Instrument operational support for local scientists, facilities, data acquisition, etc will be provided by the host nation. @-------------------------------------------------------------------- Title: What is Unusual About the 2005 January 20 SEP Event? Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Usoskin, I. Bibliographic Code: 2005AGUFMSH23A0318G Abstract We report on the solar energetic particle (SEP) event of 2005 January 20 that had an associated ground level enhancement (GLE). The Solar and Heliospheric Observatory (SOHO) spacecraft observed a CME, which was among the fastest of cycle 23 CMEs. This event is consistent with the results that the GLE-associated CMEs represent the fastest known population of CMEs. A metric type II burst started before the proton injection time, suggesting that a coronal shock was formed before high-energy protons were released at the Sun. These 2005 January 20 event is consistent with the current paradigm that large SEP events originate in CME-driven shocks. We also determined the height of the CME at two time marks: the metric type II onset (2.1 Rs) and the proton injection time (4.5 Rs). At a height of 4.5 Rs the CME should have attained the maximum speed, thus driving the strongest shocks. We discuss the estimation of the CME speed given that the coronagraph observations were hampered by the SEPs arriving at the SOHO spacecraft. We also discuss the arrival of the CME-associated plasma and shock at 1 AU. Work supported by NASA/LWS and NSF/SHINE programs. @-------------------------------------------------------------------- Title: Space-based Radio Imaging at Frequencies below the Ionospheric Cutoff with SIRA Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio, L. D.; Bale, S. D.; Howard, R. E.; Jones, D. L.; Kasper, J. C.; Reiner, M. J.; Weiler, K. W. Bibliographic Code: 2005AAS...207.2308M Abstract No present or approved spacecraft mission has the capability to provide high angular resolution imaging of solar or magnetospheric radio bursts or of the celestial sphere at frequencies below the ionospheric cutoff. In this presentation, we review a MIDEX-class mission to perform such imaging in the frequency range 30 kHz to 15 MHz. The focus of the mission, the Solar Imaging Radio Array (SIRA), is solar and exploration-oriented, with emphasis on improved understanding and application of radio bursts associated with solar energetic particle (SEP) events and on tracking shocks and other components of coronal mass ejections (CMEs). SIRA will require 12 to 16 micro-satellites to establish a sufficient number of baselines with separations on the order of kilometers. The constellation consists of microsats located quasi-randomly on a spherical shell, initially of radius 5 km. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, earth pointing high gain antenna. The constellation will likely be placed at L1, which is the preferred location for full-time solar observations. Detailed mission science and technology goals will be reviewed. @-------------------------------------------------------------------- Title: A universal characteristic of type II radio bursts Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro, S.; Kaiser, M. L. Bibliographic Code: 2005JGRA..11012S08A Abstract We present a study on the spectral properties of interplanetary type II radio bursts observed by the Radio and Plasma Wave (WAVES) experiment on board the Wind spacecraft. We investigated the relative bandwidth of the type II radio bursts observed by WAVES from 1997 up to 2003. We obtained three sets of events, based on the frequency domain of occurrence: 109 events in the low-frequency domain (30 KHz to 1000 kHz, detected by the RAD1 receiver), 216 events in the high-frequency domain (1-14 MHz, observed by the RAD2 receiver), and 73 events that spanned both domains (RAD1 and RAD2). Statistical results show that the average bandwidth-to-frequency ratio (BFR) was 0.28 +/- 0.15, 0.26 +/- 0.16, and 0.32 +/- 0.15 for RAD1, RAD2, and RAD1 + RAD2, respectively. We compared our results with those obtained for ISEE-3 type II bursts and found a difference in the average BFR, which seems to be due to a selection effect. The BFR of the WAVES type II bursts is similar to that of metric type II bursts reported in published works. This suggests that the BFR is a universal characteristic, irrespective of the spectral domain. Finally, we also studied the BFR evolution with heliocentric distance using white-light observation of the associated coronal mass ejections. We found that the BFR remains roughly constant in the SOHO/LASCO field of view (i.e., from 2.1 to 32 solar radii), while the bandwidth itself decreases. @-------------------------------------------------------------------- Title: Type II radio bursts and energetic solar eruptions Authors: Gopalswamy, N.; Aguilar-Rodriguez, E.; Yashiro, S.; Nunes, S.; Kaiser, M. L.; Howard, R. A. Bibliographic Code: 2005JGRA..11012S07G Abstract We report on a study of type II radio bursts from the Wind/WAVES experiment in conjunction with white-light coronal mass ejections (CME) from the Solar and Heliospheric Observatory (SOHO). The type II bursts considered here have emission components in all the spectral domains: metric, decameter-hectometric (DH) and kilometric (km), so we refer to them as m-to-km type II bursts. CMEs associated with the m-to-km type II bursts were more energetic than those associated with bursts in any single wavelength regime. CMEs associated with type II bursts confined to the metric domain were more energetic (wider and faster) than the general population of CMEs but less energetic than CMEs associated with DH type II bursts. Thus the CME kinetic energy seems to organize the life time of the type II bursts. Contrary to previous results, the starting frequency of metric type II bursts with interplanetary counterparts seems to be no different from that of type II bursts without interplanetary counterparts. We also verified this by showing that the average CME height at the onset time of the type II bursts is the same for the two metric populations. The majority (78%) of the m-to-km type II bursts were associated with solar energetic particle (SEP) events. The solar sources of the small fraction of m-to-km type II bursts without SEP association were poorly connected to the observer near Earth. Finally, we found that the m-to-km type II bursts were associated with bigger flares compared to the purely metric type II bursts. @-------------------------------------------------------------------- Title: Visibility of coronal mass ejections as a function of flare location and intensity Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Michalek, G.; Howard, R. A. Bibliographic Code: 2005JGRA..11012S05Y Abstract We report the visibility (detection efficiency) of coronal mass ejections (CMEs) of the Large Angle Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO). We collected 1301 X-ray flare events (above C3 level) detected by the GOES satellite and examined their CME associations using data from LASCO coronagraphs. The CME visibility was examined using the longitudinal variation of CME association of X-ray flares, under the assumption that all CMEs associated with limb flares are detectable by LASCO. Our findings are (1) the CME association rate clearly increased with X-ray flare size from 20% for C-class flares (between C3 and C9 levels) to 100% for huge flares (above X3 level), (2) all CMEs associated with X-class flares were detected by the LASCO coronagraphs, while half (25-67%) of CMEs associated with C-class flares were invisible. We examined the statistical properties of the flare-associated CMEs and compared them by flare size and longitude. CMEs associated with X-class flares were significantly faster (median 1556 km/s) and wider (median 244°) than those of CMEs associated with disk C-class flares (432 km/s, 68°). We conclude that all fast and wide CMEs are detectable by LASCO, but slow and narrow CMEs may not be visible when the CMEs originate from the disk center. @-------------------------------------------------------------------- Title: Flare-generated shock evolution and geomagnetic storms during the ``Halloween 2003 epoch'': 29 October to 2 November Authors: Wu, Chin-Chun; Wu, S. T.; Dryer, M.; Fry, C. D.; Berdichevsky, D.; Smith, Z.; Detman, T.; Gopalswamy, N.; Skoug, R.; Zurbuchen, T.; Smith, C. Bibliographic Code: 2005JGRA..11009S17W Abstract The October/November 2003 (``Halloween 2003'') epoch of intense solar flares provided an opportunity to test the results of earlier parametric 1.5 MHD studies of interacting interplanetary shock waves. These preliminary studies used an adaptive numerical grid that made it possible to identify products of these interactions. During 28 October to 2 November 2003, three shocks generated by four solar flares were observed at the L1 libration point by ACE/SWEPAM/SWICS/MAG. Two very distinct geomagnetic storms, associated with two of these flares (X17/4B and X10/2B), rank as two of the largest storms of solar cycle 23. The purpose of this paper is to present the use of an adaptive grid 1.5-dimensional MHD model that is initiated at the solar surface to study in detail the three shocks observed at L1 that were generated by the four solar flares. Accordingly, four separate pressure pulses, at the appropriate times and with different strengths and duration, determined via a trial and error procedure, are introduced on the Sun to mimic the four flares. The results show that the simulated solar wind velocity temporal profiles successfully matched the observations at L1. The major objective, to demonstrate the detailed nature of interacting shocks and some of their products after origination from closely spaced solar events, is achieved. In addition, the MHD model is able to suggest the solar sources that are associated with specific geomagnetic storms at Earth. @-------------------------------------------------------------------- Title: Coronal mass ejections and other extreme characteristics of the 2003 October-November solar eruptions Authors: Gopalswamy, N.; Yashiro, S.; Liu, Y.; Michalek, G.; Vourlidas, A.; Kaiser, M. L.; Howard, R. A. Bibliographic Code: 2005JGRA..11009S15G Abstract Fast coronal mass ejections (CMEs), X-class flares, solar energetic particle (SEP) events, and interplanetary shocks were abundantly observed during the episode of intense solar activity in late October and early November 2003. Most of the 80 CMEs originated from three active regions (NOAA ARs 484, 486, and 488). We compare the statistical properties of these CMEs with those of the general population of CMEs observed during cycle 23. We find that (1) the 2003 October-November CMEs were fast and wide on the average and hence were very energetic, (2) nearly 20 percent of the ultrafast CMEs (speed >=2000 km s^-1) of cycle 23 occurred during the October-November interval, including the fastest CME of the study period (~2700 km s^-1 on 4 November 2003 at 1954 UT), (3) the rate of full-halo CMEs was nearly four times the average rate during cycle 23, (4) at least sixteen shocks were observed near the Sun, while eight of them were intercepted by spacecraft along the Sun-Earth line, (5) the CMEs were highly geoeffective: the resulting geomagnetic storms were among the most intense of cycle 23, (6) the CMEs were associated with very large SEP events, including the largest event of cycle 23. These extreme properties were commensurate with the size and energy of the associated active regions. This study suggests that the speed of CMEs may not be much higher than ~3000 km s^-1, consistent with the free energy available in active regions. An important practical implication of such a speed limit is that the Sun-Earth travel times of CME-driven shocks may not be less than ~0.5 day. Two of the shocks arrived at Earth in <24 hours, the first events in ~30 years and only the 14th and 15th documented cases of such events since 1859. @-------------------------------------------------------------------- Title: Introduction to violent Sun-Earth connection events of October-November 2003 Authors: Gopalswamy, N.; Barbieri, L.; Cliver, E. W.; Lu, G.; Plunkett, S. P.; Skoug, R. M. Bibliographic Code: 2005JGRA..11009S00G Abstract The solar-terrestrial events of late October and early November 2003, popularly referred to as the Halloween storms, represent the best observed cases of extreme space weather activity observed to date and have generated research covering multiple aspects of solar eruptions and their space weather effects. In the following article, which serves as an abstract for this collective research, we present highlights taken from 61 of the 74 papers from the Journal of Geophysical Research, Geophysical Research Letters, and Space Weather which are linked under this special issue. (An overview of the 13 associated papers published in Geophysics Research Letters is given in the work of Gopalswamy et al. (2005a)). @-------------------------------------------------------------------- Title: A Study of the Drift Rate of Type II Radio Bursts at Different Wavelengths Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro, S.; Kaiser, M. I. Bibliographic Code: 2005ESASP.592..393A Abstract @-------------------------------------------------------------------- Title: Solar source of the largest geomagnetic storm of cycle 23 Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Lepping, R. P.; Howard, R. A. Bibliographic Code: 2005GeoRL..3212S09G Abstract The largest geomagnetic storm of solar cycle 23 occurred on 2003 November 20 with a Dst index of -472 nT, due to a coronal mass ejection (CME) from active region 0501. The CME near the Sun had a sky-plane speed of ~1660 km/s, but the associated magnetic cloud (MC) arrived with a speed of only 730 km/s. The MC at 1 AU (ACE Observations) had a high magnetic field (~56 nT) and high inclination to the ecliptic plane. The southward component of the MC's magnetic field was made up almost entirely of its axial field because of its east-south-west (ESW) chirality. We suggest that the southward pointing strong axial field of the MC reconnected with Earth's front-side magnetic field, resulting in the largest storm of the solar cycle 23. @-------------------------------------------------------------------- Title: Coronal Mass Ejections and Galactic Cosmic-Ray Modulation Authors: Lara, A.; Gopalswamy, N.; Caballero-López, R. A.; Yashiro, S.; Xie, H.; Valdés-Galicia, J. F. Bibliographic Code: 2005ApJ...625..441L Abstract We present a study of the long-term evolution of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronograph (LASCO) on board SOHO during the ascending, maximum, and part of the descending phases of solar cycle 23 and their relation with the modulation of galactic cosmic-ray (GCR) intensity observed at 1 AU by the Climax neutron monitor and IMP-8 spacecraft. We compare the long-term GCR modulation with the CME occurrence rate at all, low, and high latitudes, as well as the observed CME parameters (width and speed). Twenty-seven day averages of CME occurrence rates and CME properties from 1996 January to 2003 December are presented in the Appendix. The general anticorrelation between GCR intensity and the CME rate is relatively high (~-0.88). However, when we divide the CME rate into low- and high-latitude rates and compare them with the GCR intensity during the ascending phase of solar cycle 23, we find a lower anticorrelation between the low-latitude the CME rate and GCR intensity (~-0.71) and a very high anticorrelation between the high-latitude CME rate and GCR intensity (~-0.94). This suggests that, in general, CMEs could cause the decrease in the GCR flux in the inner heliosphere, as stated by the global merged interaction region (GMIR) theory. In particular, during the ascending phase of cycle 23 (qA>0), this flux comes mainly from heliospheric polar regions. Thus, high-latitude CMEs may play a central role in the long-term cosmic-ray modulation during this phase of the cycle by blocking the polar entrance of GCRs to the inner heliosphere. This study supports the scenario in which CMEs, among other structures, are the building blocks of GMIRs, although we propose that the spherical shells (GMIRs) are closed separately at polar and equatorial regions by CMEs of different latitudes. Our results suggest that all CME properties show some correlation with the GCR intensity, although there is no specific property (width, speed, or a proxy of energy) that definitely has a higher correlation with GCR intensity. @-------------------------------------------------------------------- Title: Sun-Earth Propagation Time of CMEs Originated at different Helio Longitudes Authors: Lara, A.; Gopalswamy, N.; Xie, H.; Gonzalez-Esparza, A. Bibliographic Code: 2005AGUSMSH53A..10L Abstract We present a study of the transport of coronal mass ejections (CMEs) in the interplanetary medium and the probability that they, or the associated shocks, reach the Earth surroundings when they are ejected in different Helio-longitudes. To reach this goal we choose the CME events associated with the active region 0486 which crosses the solar disk during October - November 2003 and produced several CMEs during its crossing from East to West limb. We measured and analyzed the speed profile of each event, we found that the speed profile of halos and partial-halo CMEs are very symmetric and an elliptical model seems to fit the profiles very well. Using a cone model we determine the space direction of CMEs and then, the most probable speed in the Sun-Earth direction. Using these speeds, we applied the CME travel time empirical model to determine the near Earth arrival times of both interplanetary CME and related shock. We found that the difference between the predicted and observed arrival times increase with the Helio-longitude of the CME. To help in the identification of CME - 1 AU shocks and to validate the empirical model, we use 2D numerical simulations of the events. @-------------------------------------------------------------------- Title: Improved Empirical CME Arrival Time Model Via Cone Model Authors: Xie, H.; Gopalswamy, N.; Ofman, L.; Michalek, G.; Lara, A.; Yashiro, S. Bibliographic Code: 2005AGUSMSH53A..09X Abstract In this study, we compare the results obtained from two cone models and carry out the statistical study of the distribution of the actual size and space speed of Coronal Mass Ejections (CMEs). We improved the existing empirical CME arrival (ECA) model, based on previously developed empirical models and provided the prediction of CME transit time from the Sun to the Earth. The previous ECA model was in good agreement with the observations for high-speed CMEs. However, the agreement was not as good for low-speed events. One of possible reasons may be due to errors caused by the significant scatter of CME projection speeds in low projected-speed events. Using the cone models we reduced the errors and improved the accuracy of the ECA model by applying the cone models to halo CMEs erupted from near disk center of the Sun (within < 30 deg.) to determine the actual speed. We found that both cone models provide similar improved accuracy for the arrival time. @-------------------------------------------------------------------- Title: Photospheric sources of very fast coronal mass ejections Authors: Yurchyshyn, V.; Yashiro, S.; Gopalswamy, N. Bibliographic Code: 2005AGUSMSH51C..04Y Abstract We identified photospheric sources for 39 very fast (v > 1100 km/s) front-side coronal mass ejections that erupted between 1999 and 2001. For our study we used data on CMEs and their sources provided by the CME Catalog, SOHO spacecraft (LASCO, EIT, MDI), Big Bear Solar Observatory (Halpha, magnetograms), Mount Wilson Observatory (sunspot drawings) and Joint USAF/NOAA active region summary. Our results are as follows. We distinguished three different groups of active regions which are responsible for very fast CMEs: 1) Complex delta spots (21 events). This group of active regions is characterized by the presence of at least two large opposite polarity sunspots located close to each other. 2) Simple delta spots (8 events). A typical configuration of this type consists of one large twisted tadpole-shaped sunspot, surrounded by many small satellite-sunspots. 3) Extended magnetic regions, which consist of two adjacent decaying active regions or a new active region emerging inside a decaying active region. @-------------------------------------------------------------------- Title: Statistical Study of Shocks and CMEs Associated With Interplanetary Type II Bursts Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro, S.; Kaiser, M. L. Bibliographic Code: 2005AGUSMSH43A..04A Abstract We present a study of some spectral properties associated with interplanetary Type II radio emission. Type II radio bursts are signatures of violent eruptions from the Sun that result in shock waves propagating through the corona and the interplanetary medium. We investigated the relative bandwidth of all the type II bursts observed by the Radio and Plasma Wave Experiment (WAVES) on board the Wind spacecraft from 1997 up to 2003. We obtained three sets of events, based on the frequency domain of occurrence: 109 events in the low frequency domain (30 KHz to 1000 kHz detected by the RAD1 receiver), 216 events in the high frequency domain (1-14 MHz, observed by the RAD2 receiver), and 73 events that spanned both domains (RAD1 and RAD2). We present statistical results for the bandwidth-to-frequency ratio (BFR) in the three subsets as well as a comparision of our results with the Type II solar radio bursts observed by ISEE-3 radio experiment, which is similar to WAVES/RAD1. We analyzed the bandwidth and BFR evolution with the heliocentric distance as well as an analysis of drift rate magnitude of type II radio bursts and its starting frequency. We also present some properties of shocks and coronal mass ejections associated with interplanetary type II bursts. This work is partially supported by NSF/SHINE (ATM 0204588) @-------------------------------------------------------------------- Title: Putting the Rubber to the Road: The Whos, Whys and Hows of the International Heliophysical Year 2007 Authors: Thompson, B. J.; Davila, J. M.; Drobnes, E.; Gopalswamy, N.; Wesenberg, R. P. Bibliographic Code: 2005AGUSM.U23A..07T Abstract In 1957 a program of international research, inspired by the International Polar Years of 1882 and 1932, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. Fifty years later, the world's science community will again come together for international programs of scientific collaboration: the International Heliophysical Year (IHY), the electronic Geophysical Year (eGY), and the International Polar Year (IPY) 2007. This time, research will extend out into the heliosphere to focus on solar-terrestrial-planetary interactions. The ambitious plans for the IHY, eGY and IPY incorporate the activities of scientists in 191 nations, the "IGY Gold" Historical Preservation initiative, a series of coordinated campaigns involving more than 100 instruments and models, education and public outreach programs, a developing nations instrument development program, and opportunities for supported research worldwide. The presentation will focus on the efforts and operations which will make these activities possible. @-------------------------------------------------------------------- Title: Estimation of Projection Effect of CMEs from the Onset Time of the Shock-Associated Type III Radio Burst Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2005AcA....55..151M Abstract We present a new possibility to estimate the projection effects on coronal mass ejection (CME) measurements. It is well known that coronagraphic observations of CMEs are subject to projection effects. Fortunately, the WIND/WAVES observations of type III radio bursts associated with shock waves are free from projection effects. We assume that (1) high energy electrons are produced at the shock front ahead of the CME, and (2) the radio burst starts when the shock reaches open field lines (approx 3 R_odot). In other words, the onset time of the radio burst corresponds to the time when the CME leading edge reaches 3 R_odot. The difference between the onset times of CMEs and radio bursts should be strongly correlated with the position of CMEs on the Sun. This correlation seems to be strongly dependent on solar activity. Using particular linear fits on the scatter plots, we can determine the source location of CMEs and tell how much the projection effect can really affect CME measurements. @-------------------------------------------------------------------- Title: Introduction to the special section: Violent Sun-Earth connection events of October-November 2003 Authors: Gopalswamy, N.; Barbieri, L.; Lu, G.; Plunkett, S. P.; Skoug, R. M. Bibliographic Code: 2005GeoRL..3203S01G Abstract During 2003 October and November, a series of solar eruptions occurred from three solar active regions. Some of these eruptions were extreme in terms of their origin (source properties) and heliospheric consequences. This paper summarizes the first results of the analysis of these violent Sun-Earth connection events. @-------------------------------------------------------------------- Title: Solar Imaging Radio Array (SIRA): a multispacecraft mission Authors: MacDowall, R. J.; Bale, S. D.; Demaio, L.; Gopalswamy, N.; Jones, D. L.; Kaiser, M. L.; Kasper, J. C.; Reiner, M. J.; Weiler, K. W. Bibliographic Code: 2005SPIE.5659..284M Abstract The Solar Imaging Radio Array (SIRA) is a mission to perform aperture synthesis imaging of low frequency solar, magnetospheric, and astrophysical radio bursts. The primary science targets are coronal mass ejections (CMEs), which drive shock waves that may produce radio emission. A space-based interferometer is required, because the frequencies of observation (<15 MHz) are cutoff by the ionosphere. SIRA will require a 12 to 16 microsatellite constellation to establish a sufficient number of baselines with separations on the order of kilometers. The microsats will be located quasi-randomly on a spherical shell, initially of diameter 10 km or less. The baseline microsat, as presented here, is 3-axis stabilized with a body-mounted, earth-directed high gain antenna and an articulated solar array; this design was developed by the Integrated Mission Design Center (IMDC) at NASA Goddard Space Flight Center (GSFC). A retrograde orbit at a distance of ~500,000 km from Earth was selected as the preferred orbit because the 8 Mbps downlink requirement is easy to meet, while keeping the constellation sufficiently distant from terrestrial radio interference. Also, the retrograde orbit permits imaging of terrestrial magnetospheric radio sources from varied perspectives. The SIRA mission serves as a pathfinder for space-based satellite constellations and for spacecraft interferometry at shorter wavelengths. It will be proposed to the NASA MIDEX proposal opportunity in mid-2005. @-------------------------------------------------------------------- Title: Statistical Distributions of Speeds of Coronal Mass Ejections Authors: Yurchyshyn, V.; Yashiro, S.; Abramenko, V.; Wang, H.; Gopalswamy, N. Bibliographic Code: 2005ApJ...619..599Y Abstract We studied the distribution of plane-of-sky speeds determined for 4315 coronal mass ejections (CMEs) detected by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliospheric Observatory (SOHO LASCO). We found that the speed distributions for accelerating and decelerating events are nearly identical and to a good approximation they can be fitted with a single lognormal distribution. This finding implies that, statistically, there is no physical distinction between the accelerating and the decelerating events. The lognormal distribution of the CME speeds suggests that the same driving mechanism of a nonlinear nature is acting in both slow and fast dynamical types of CMEs. @-------------------------------------------------------------------- Title: Coronal Mass Ejections and Ground Level Enhancements Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Usoskin, I. Bibliographic Code: 2005ICRC....1..169G Abstract @-------------------------------------------------------------------- Title: CMEs and Long-Lived Geomagnetic Storms: A Case Study Authors: Xie, H.; Gopalswamy, N.; Manoharan, P. K.; Yashiro, S.; Lara, A.; Lepri, S. Bibliographic Code: 2005IAUS..226..475X Abstract We studied the relationship between successive coronal mass ejections (CMEs) and a long-lived geomagnetic storm (LLGMS) by examining the 1998 May 4 event. Five successive CMEs from the same active region and four interplanetary shocks were found to be associated with this LLGMS. We investigated the effect of successive and interacting CMEs on the LLGMS. @-------------------------------------------------------------------- Title: CME Interaction and the Intensity of Solar Energetic Particle Events Authors: Gopalswamy, N.; Yashiro, S.; Krucker, S.; Howard, R. A. Bibliographic Code: 2005IAUS..226..367G Abstract Large Solar Energetic Particles (SEPs) are closely associated with coronal mass ejections (CMEs). The significant correlation observed between SEP intensity and CME speed has been considered as the evidence for such a close connection. The recent finding that SEP events with preceding wide CMEs are likely to have higher intensities compared to those without was attributed to the interaction of the CME-driven shocks with the preceding CMEs or with their aftermath. It is also possible that the intensity of SEPs may also be affected by the properties of the solar source region. In this study, we found that the active region area has no relation with the SEP intensity and CME speed, thus supporting the importance of CME interaction. However, there is a significant correlation between flare size and the active region area, which probably reflects the spatial scale of the flare phenomenon as compared to that of the CME-driven shock. @-------------------------------------------------------------------- Title: An empirical model to predict the 1-AU arrival of interplanetary shocks Authors: Gopalswamy, N.; Lara, A.; Manoharan, P. K.; Howard, R. A. Bibliographic Code: 2005AdSpR..36.2289G Abstract We extend the empirical coronal mass ejection (CME) arrival model of Gopalswamy et al. [Gopalswamy, N. et al. Predicting the 1-AU arrival times of coronal mass ejections, J. Geophys. Res. 106, 29207, 2001] to predict the 1-AU arrival of interplanetary (IP) shocks. A set of 29 IP shocks and the associated magnetic clouds observed by the Wind spacecraft are used for this study. The primary input to this empirical shock arrival model is the initial speed of white-light CMEs obtained using coronagraphs. We use the gas dynamic piston-shock relationship to derive the ESA model which provides a simple means of obtaining the 1-AU speed and arrival times of interplanetary shocks using CME speeds. @-------------------------------------------------------------------- Title: Recent advances in the long-wavelength radio physics of the Sun Authors: Gopalswamy, N. Bibliographic Code: 2004P&SS...52.1399G Abstract Solar radio bursts at long wavelengths provide information on solar disturbances such as coronal mass ejections (CMEs) and shocks at the moment of their departure from the Sun. The radio bursts also provide information on the physical properties (density, temperature and magnetic field) of the medium that supports the propagation of the disturbances with a valuable cross-check from direct imaging of the quiet outer corona. The primary objective of this paper is to review some of the past results and highlight recent results obtained from long-wavelength observations. In particular, the discussion will focus on radio phenomena occurring in the outer corona and beyond in relation to those observed in white light. Radio emission from nonthermal electrons confined to closed and open magnetic structures and in large-scale shock fronts will be discussed with particular emphasis on its relevance to solar eruptions. Solar cycle variation of the occurrence rate of shock-related radio bursts will be discussed in comparison with that of interplanetary shocks and solar proton events. Finally, case studies describing the newly-discovered radio signatures of interacting CMEs will be presented. @-------------------------------------------------------------------- Title: Intensity variation of large solar energetic particle events associated with coronal mass ejections Authors: Gopalswamy, N.; Yashiro, S.; Krucker, S.; Stenborg, G.; Howard, R. A. Bibliographic Code: 2004JGRA..10912105G Abstract We studied the coronal mass ejections (CMEs) and flares associated with large solar energetic particle (SEP) events of solar cycle 23 (1996-2002) in order to determine what property of the solar eruptions might order the SEP intensity. The SEP events were divided into three groups: (1) events in which the primary CME was preceded by one or more wide CMEs from the same solar source, (2) events with no such preceding CMEs, and (3) events in which the primary CME might have interacted with a streamer or with a nearby halo CME. The SEP intensities are distinct for groups 1 and 2 although the CME properties were nearly identical. Group 3 was similar to group 1. The primary findings of this study are as follows: (1) Higher SEP intensity results whenever a CME is preceded by another wide CME from the same source region. (2) The average flare size was also larger for high-intensity SEP events. (3) The intensity of SEP events with preceding CMEs showed a tighter correlation with CME speed. The extent of scatter in the CME speed versus SEP intensity plots was reduced when various subgroups were considered separately. (4) The intensities of energetic electrons were better correlated with flare size than with CME speed. (5) The SEP intensity showed poor correlation with the flare size, except for group 3 events. Since only a third of the events did not have preceding CMEs, we conclude that the majority of SEP producing CMEs propagate through the near-Sun interplanetary medium severely disturbed and distorted by the preceding CMEs. Furthermore, the preceding CMEs are faster and wider on the average, so they may provide seed particles for CME-driven shocks that follow. Therefore we conclude that the differing intensities of SEP events in the two groups may not have resulted due to the inherent properties of the CMEs. The presence of preceding CMEs seems to be the discriminating characteristic of the high- and low-intensity SEP events. @-------------------------------------------------------------------- Title: Solar Imaging Radio Array (SIRA): Imaging solar, magnetospheric, and astrophysical sources at < 15 MHz Authors: Howard, R.; MacDowall, R.; Gopalswamy, N.; Kaiser, M. L.; Reiner, M. J.; Bale, S.; Jones, D.; Kasper, J.; Weiler, K. Bibliographic Code: 2004DPS....36.1424H Abstract The Solar Imaging Radio Array (SIRA) is a mission to perform aperture synthesis imaging of low frequency solar, magnetospheric, and astrophysical radio bursts. The primary science targets are coronal mass ejections (CMEs), which drive radio emission producing shock waves. A space-based interferometer is required, because the frequencies of observation (<15 MHz) do not penetrate the ionosphere. As such, the SIRA mission serves as a lower frequency counterpart to LWA, LOFAR, and similar ground-based radio imaging arrays. SIRA will require 12 to 16 microsatellites to establish a sufficient number of baselines with separations on the order of kilometers. The microsat constellation consists of microsats located quasi-randomly on a spherical shell, initially of radius 5 km or less. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, earth pointing high gain antenna. A retrograde orbit at 500,000 km from Earth was selected as the preferred orbit because it reduces the downlink requirement while keeping the microsats sufficiently distant from terrestrial radio interference. Also, the retrograde orbit permits imaging of terrestrial magnetospheric radio sources from varied perspectives. The SIRA mission serves as a pathfinder for space-based satellite constellations and for spacecraft interferometry at shorter wavelengths. It will be proposed to the NASA MIDEX proposal opportunity in mid-2005. @-------------------------------------------------------------------- Title: Association of Coronal Mass Ejections and Type II Radio Bursts with Impulsive Solar Energetic Particle Events Authors: Yashiro, S.; Gopalswamy, N.; Cliver, E. W.; Reames, D. V.; Kaiser, M. L.; Howard, R. A. Bibliographic Code: 2004ASPC..325..401Y Abstract We report the association of impulsive solar energetic particle (SEP) events with coronal mass ejections (CMEs) and metric type II radio bursts. We identified 38 impulsive SEP events using the WIND/EPACT instrument and their CME association was investigated using white light data from SOHO/LASCO. We found that (1) at least ˜ 28--39 % of impulsive SEP events were associated with CMEs, (2) only 8--13 % were associated with metric type II radio bursts. The statistical properties of the associated CMEs were investigated and compared with those of general CMEs and CMEs associated with large gradual SEP events. The CMEs associated with impulsive SEP events were significantly slower (median speed of 613 kmps) and narrower (49 deg) than those of CMEs associated with large gradual SEP events (1336 kmps, 360 deg), but faster than the general CMEs (408 kmps). @-------------------------------------------------------------------- Title: Improved Empirical CME Arrival Time Prediction Model Authors: Xie, H.; Gopalswamy, N.; Lara, A.; Yashiro, S. Bibliographic Code: 2004AGUFMSH53B0324X Abstract We have successfully developed an innovative analytical method to determine the angular width and propagation orientation of Halo Coronal Mass Ejections (Xie et al. 2003). We will apply this new method to improve the existing empirical space weather forecasting models (e.g., Gopalswamy et al., 2001). Gopalswamy et al. (2001) presented an empirical model to provide the predication of CME transit time from the Sun to the Earth. The model is in good agreement with the observations for high-speed CMEs. However, the agreement is not good for low-speed events. One of possible reasons may be due to errors caused by the significant scatter of CME prjection speeds used in the model. Using our new method can determine the actual speed of CMEs and thus reduce the errors and improve the model. @-------------------------------------------------------------------- Title: Brightness Characteristics of Halo CMEs Authors: Lara, A.; Gopalswamy, N.; Michalek, G.; Xie, H.; Yashiro, S. Bibliographic Code: 2004AGUFMSH53B0316L Abstract It is generally accepted that halo Coronal Mass Ejections (CMEs) are regular, low latitude, CMEs traveling towards (or away FROM) the observer. The association between halo CMEs and solar energetic particles events (SEPs) and Type II bursts is higher compared to regular CMEs. Halo CMEs are observed up to large heliocentric distances as compared to the regular CMEs. This is somewhat contradictory to the theory of Thomson scattering because the visibility conditions for halo CMEs are rather poor, assuming that the longitudinal widths of halo CMEs are the similar to those of regular CMEs. In this paper, we present some observational characteristics of halo CMEs, such as high brightness at large distances and symmetry in the velocity space. The CMEs were observed by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO). We also present a possible model that explains the apparent contradiction @-------------------------------------------------------------------- Title: Radio-quiet Fast Coronal Mass Ejections Authors: Gopalswamy, N.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A. Bibliographic Code: 2004AGUFMSH23A..05G Abstract Coronal mass ejections (CMEs) drive shocks in the interplanetary medium that produce type II radio emission. These CMEs are faster and wider on the average, than the general population of CMEs. However, when we start from fast (speed > 900 km/s) and wide (angular width > 60 degrees), more than half of them are not associated with radio bursts. In order to understand why these CMEs are radio quiet, we collected all the fast and wide (FW) CMEs detected by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) and isolated those without associated type II radio bursts. The radio bursts were identified in the dynamic spectra of the Radio and Plasma Wave (WAVES) Experiment on board the Wind spacecraft. We also checked the list against metric type II radio bursts reported in Solar Geophysical Data and isolated those without any radio emission. This exercise resulted in about 140 radio-quiet FW CMEs. We identified the source regions of these CMEs using the Solar Geophysical Data listings, cross-checked against the eruption regions in the SOHO/EIT movies. We explored a number of possibilities for the radio-quietness: (i) Source region being too far behind the limb, (ii) flare size, (iii) brightness of the CME, and (iv) the density of the ambient medium. We suggest that a combination of CME energy and the Alfven speed profile of the ambient medium is primarily responsible for the radio-quietness of these FW CMEs. @-------------------------------------------------------------------- Title: The Solar Imaging Radio Array (SIRA) Mission Authors: Jones, D. L.; MacDowall, R.; Gopalswamy, N.; Kaiser, M.; Reiner, M.; Demaio, L.; Weiler, K.; Kasper, J.; Bale, S.; Howard, R. Bibliographic Code: 2004AAS...205.1012J Abstract The Solar Imaging Radio Array will be proposed to NASA as a Medium Explorer (MIDEX) mission by a team of investigators at GSFC, JPL, NRL, MIT, and UC Berkeley. The main science goal of the mission is imaging and tracking of solar radio bursts, particularly those associated with coronal mass ejections, and understanding their evolution and influence on Earth's magnetosphere. Related goals are mapping the 3-dimensional morphology of the interplanetary magnetic field and improving the prediction of geomagnetic storms. A number of topics in galactic and extragalactic astrophysics will also be addressed by SIRA. The mission concept is a free-flying array of about 16 small, inexpensive satellites forming an aperture synthesis interferometer in space. By observing from above the ionosphere, and far from terrestrial radio interference, SIRA will cover frequencies between a few tens of kHz up to 15 MHz. This wide spectral window is essentially unexplored with high angular resolution. Part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. @-------------------------------------------------------------------- Title: A Global Picture of CMEs in the Inner Heliosphere Authors: Gopalswamy, N. Bibliographic Code: 2004ASSL..317..201G Abstract @-------------------------------------------------------------------- Title: Energy partition in two solar flare/CME events Authors: Emslie, A. G.; Kucharek, H.; Dennis, B. R.; Gopalswamy, N.; Holman, G. D.; Share, G. H.; Vourlidas, A.; Forbes, T. G.; Gallagher, P. T.; Mason, G. M.; Metcalf, T. R.; Mewaldt, R. A.; Murphy, R. J.; Schwartz, R. A.; Zurbuchen, T. H. Bibliographic Code: 2004JGRA..10910104E Abstract Using coordinated observations from instruments on the Advanced Composition Explorer (ACE), the Solar and Heliospheric Observatory (SOHO), and the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we have evaluated the energetics of two well-observed flare/CME events on 21 April 2002 and 23 July 2002. For each event, we have estimated the energy contents (and the likely uncertainties) of (1) the coronal mass ejection, (2) the thermal plasma at the Sun, (3) the hard X-ray producing accelerated electrons, (4) the gamma-ray producing ions, and (5) the solar energetic particles. The results are assimilated and discussed relative to the probable amount of nonpotential magnetic energy available in a large active region. @-------------------------------------------------------------------- Title: Interplanetary Radio Bursts Authors: Gopalswamy, N. Bibliographic Code: 2004ASSL..314..305G Abstract Nonthermal radio bursts in the interplanetary medium indicate the far-reaching effect of solar eruptions that inject energetic particles, plasmas and shock waves into the inner heliosphere. More than half a century of ground-based observations and subsequent space-based observations exist on this phenomena. In this paper, I summarize the understanding we have gained on the type III and type II radio bursts, which are indicative of electron beams and shocks, respectively. Observations in the new radio window (1-14 MHz) from Wind/WAVES have not only confirmed previous results, but also led to a number of new discoveries. Availability of simultaneous white light (SOHO) and radio (Wind) observations from the same spatial domain in the near-Sun IP medium is largely responsible for these discoveries on the IP propagation of CMEs, so this paper discusses radio bursts in the context of white light observations. After exploring the origin of normal, complex and storm type III bursts, I discuss the type II bursts and their relation to coronal mass ejections. Finally I discuss some of the recent developments on IP radio emission. @-------------------------------------------------------------------- Title: Arrival time of halo coronal mass ejections in the vicinity of the Earth Authors: Michalek, G.; Gopalswamy, N.; Lara, A.; Manoharan, P. K. Bibliographic Code: 2004A&A...423..729M Abstract We describe an empirical model to predict the 1-AU arrival time of halo CMEs. This model is based on the effective acceleration described by Gopalswamy et al. (\cite{Gopalswamy00}a, Geophys. Res. Lett., 27, 145). We verify the Helios/Pioneer Venus Orbiter(PVO) estimation of the effective acceleration profile (Gopalswamy et al. \cite{Gopalswamy01}a, J. Geophys. Res., 106, 29207) by considering all full halo CMEs recorded by SOHO/LASCO coronagraphs until the end of 2002. In comparison with previous studies, the present work includes CMEs of a wider range of initial velocities. To improve the accuracy of prediction, we propose to introduce the effective acceleration from two groups of CMEs only, which are expected to have no acceleration cessation at any place between the Sun and Earth. In addition, we consider acceleration cessation distance dependent on initial velocities of a given event CME. For a detailed analysis of this model, we examine projected sky-plane and space speeds (Michalek et al. \cite{Michalek03}, ApJ, 584, 472) of CMEs. We show that a correct acceleration profile is crucial for the estimation of 1 AU arrival time of halo CMEs. We estimate that the CME arrival times can be predicted with an average error of 9 and 11 h for space and sky-plane initial velocities, respectively. Table 1 is only available in electronic form at http://www.edpsciences.org @-------------------------------------------------------------------- Title: Kinematics of coronal mass ejections between 2 and 30 solar radii. What can be learned about forces governing the eruption? Authors: Vrsnak, B.; Ruzdjak, D.; Sudar, D.; Gopalswamy, N. Bibliographic Code: 2004A&A...423..717V Abstract Kinematics of more than 5000 coronal mass ejections (CMEs) measured in the distance range 2-30 solar radii is investigated. A distinct anticorrelation between the acceleration, a, and the velocity, v, is found. In the linear form, it can be represented as a=-k₁(v-v₀), where v₀=400 km s^-1, i.e., most of CMEs faster than 400 km s^-1 decelerate, whereas slower ones generally accelerate. After grouping CMEs into the width and mean-distance bins, it was found that the slope k₁ depends on these two parameters: k₁ is smaller for CMEs of larger width and mean-distance. Furthermore, the obtained CME subsets show distinct quadratic-form correlations, of the form a= -k₂ (v-v₀)| v-v₀|. The value of k₂ decreases with increasing distance and width, whereas v₀ increases with the distance and is systematically larger than the slow solar wind speed by 100-200 km s^-1. The acceleration-velocity relationship is interpreted as a consequence of the aerodynamic drag. The excess of v₀ over the solar wind speed is explained assuming that in a certain fraction of events the propelling force is still acting in the considered distance range. In most events the inferred propelling force acceleration at 10 solar radii ranges between a_L=0 and 10 m s^-2, being on average smaller at larger distances. However, there are also events that show a_L>50 m s^-2, as well as events indicating a_L<0. Implications for the interplanetary motion of CMEs are discussed, emphasizing the prediction of the 1 a.u. arrival time. Appendices A and B are only available in electronic form at http://www.edpsciences.org @-------------------------------------------------------------------- Title: A catalog of white light coronal mass ejections observed by the SOHO spacecraft Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; St. Cyr, O. C.; Plunkett, S. P.; Rich, N. B.; Howard, R. A. Bibliographic Code: 2004JGRA..10907105Y Abstract The Solar and Heliospheric Observatory (SOHO) mission's white light coronagraphs have observed nearly 7000 coronal mass ejections (CMEs) between 1996 and 2002. We have documented the measured properties of all these CMEs in an online catalog. We describe this catalog and present a summary of the statistical properties of the CMEs. The primary measurements made on each CME are the apparent central position angle, the angular width in the sky plane, and the height (heliocentric distance) as a function of time. The height-time measurements are then fitted to first- and second-order polynomials to derive the average apparent speed and acceleration of the CMEs. The statistical properties of CMEs are (1) the average width of normal CMEs (20° < width <= 120°) increased from 47° (1996; solar minimum) to 61° (1999; early phase of solar maximum) and then decreased to 53° (2002; late phase of solar maximum), (2) CMEs were detected around the equatorial region during solar minimum, while during solar maximum CMEs appear at all latitudes, (3) the average apparent speed of CMEs increases from 300 km s^-1 (solar minimum) to 500 km s^-1 (solar maximum), (4) the average apparent speed of halo CMEs (957 km s^-1) is twice of that of normal CMEs (428 km s^-1), and (5) most of the slow CMEs (V <= 250 km s^-1) show acceleration while most of the fast CMEs (V > 900 km s^-1) show deceleration. Solar cycle variation and statistical properties of CMEs are revealed with greater clarity in this study as compared with previous studies. Implications of our findings for CME models are discussed. @-------------------------------------------------------------------- Title: Influence of coronal mass ejection interaction on propagation of interplanetary shocks Authors: Manoharan, P. K.; Gopalswamy, N.; Yashiro, S.; Lara, A.; Michalek, G.; Howard, R. A. Bibliographic Code: 2004JGRA..10906109M Abstract We studied 91 interplanetary (IP) shocks associated with coronal mass ejections (CMEs) originating within about +/-30° in longitude and latitude from the center of the Sun during 1997-2002. These CMEs cover a wide range of initial speeds of about 120 to 2400 kms^-1 and they also include a special population of 25 interacting CMEs. This study provides the characteristics of propagation effects of more number of high-speed CMEs (V_CME > 1500 kms^-1) than the data used in earlier studies. It enables to extend the shock-arrival prediction model to high-speed CMEs. The results on comparison of IP shock speed and transit time at 1 AU suggest that the shock transit time is not controlled by its final speed but is primarily determined by the initial speed of the CME and effects encountered by it during the propagation. It is found that the CME interaction tends to slow the shock and associated CME. The deviations of shock arrival times from the empirical model are considerably large for slow (V_CME < 300 kms^-1) and fast (V_CME > 800 kms^-1) CMEs. Results show that the slow and fast CMEs experience stronger effective acceleration. @-------------------------------------------------------------------- Title: Shock Evolution During 29 - 06 November 2003 period of Solar-Flare-CME-Shock-Geomagnetic Storms Authors: Wu, C.; Wu, S.; Dryer, M.; Fry, C.; Berdichevsky, D.; Smith, Z.; Gopalswamy, N.; Zurbuchen, T.; Smith, C.; Detman, T. Bibliographic Code: 2004AGUSMSH51A..14W Abstract During the period 29 October - 6 November four shocks were observed at Earth by ACE/SWEPAM/MAG and ACE/SWICS on 29 October, 30 October, 4 November, and 6 November. Two distinct and very intense geomagnetic storms, associated with the X17.2 and X10/2B flares, rank as the largest storms of Solar Cycle 23. For example, the X17.2 flare (28 October, S16E08 in AR0486), via its associated halo CME and shock wave, was responsible for the Dst = -347 nT index on 30 October 2003. We will present the use of an adaptive grid 2D MHD model to study these four shocks in detail. Accordingly, four separate pressure pulses, at the appropriate times and with different strengths and duration are introduced at the Sun to mimic the four flares. The results show that the simulated solar wind velocity time series successfully match the observations at L1. @-------------------------------------------------------------------- Title: CME Cannibalism and Long-wavelength Radio Emission During the October-November 2003 Storms Authors: Gopalswamy, N.; Kaiser, M.; Yashiro, S.; Reiner, M.; Desch, M.; MacDowall, R.; Gurnett, D.; Kurth, W.; Bougeret, J.; Vourlidas, A.; Howard, R. Bibliographic Code: 2004AGUSMSH51A..07G Abstract A spectacular interaction between two fast coronal mass ejections (CMEs) was observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board SOHO on November 4, 2003. The interaction resulted in a broadband radio enhancement in the dynamic spectrum of the Radio and Plasma Waves (WAVES) experiment on board Wind. The radio enhancement occurred when the second CME moving with a speed of 2700 km/s caught up with a slower CME (~ 600 km/s) and its dense core at a distance of 18 solar radii from the Sun. Direction finding from WAVES observations matched with the white-light location of the interaction region. The radio enhancement was brighter than the associated type II burst. We also show from the observed flux radio density and white-light source extent that the radio emission is nonthermal. The radio emission due to the colliding CMEs was also observed by Ulysses and CASSINI, which were at distances of 5 and 8.7 AU, respectively. The signatures arrived at CASSINI and Ulysses with a delay corresponding to the appropriate light travel times. Wind, Ulysses, and CASSINI were widely separated in heliocentric distance as well as angular separation, suggesting that the interaction signature is not narrowly beamed. Work supported by NASA/LWS and NSF/SHINE @-------------------------------------------------------------------- Title: Sun-Earth Propagation Time of the October - November 2003 Shocks Authors: Lara, A.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2004AGUSMSH51A..06L Abstract We computed the radial and expansion speed profiles of the CMEs that resulted in shocks detected at 1 AU, in order to evaluate the empirical shock arrival (ESA) model. The CMEs were observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board SOHO during October - November 2003 period. The shocks were detected by CELIAS/MTOF Proton Monitor on board SOHO and ACE spacecraft. The basic input to the ESA model is the CME speed. For limb events, we assume axial symmetry in order to obtain the most probable CME speed in the Sun-Earth direction. We apply the ESA model to obtain the travel times of shocks driven by Earth-directed and limb CMEs which had in situ observations at 1AU. For most cases the difference between the predicted and observed shock arrival times is negligible. We discuss these differences and their possible causes. Work supported by NASA/LWS and NSF/SHINE programs @-------------------------------------------------------------------- Title: Composition and Magnetic Structure of ICMEs at 1 AU Authors: Aguilar-Rodriguez, E.; Blanco-Cano, X.; Gopalswamy, N. Bibliographic Code: 2004AGUSMSH41A..08A Abstract We present preliminary results of a study of the charge state ratio as well as the magnetic structure characteristics of 154 interplanetary coronal mass ejections (ICMEs) observed at 1 AU by the ACE and Wind spacecrafts. Measurements of charge state composition in the solar wind combined with magnetic field structures are important to understand the physical conditions in the source regions of the solar wind. We used magnetic field (Wind and ACE), plasma (Wind) and ion composition (ACE) data over a period of time from 1998 to 2002. All the events were indentified using the low proton temperature criterion, a common plasma signature of ICMEs. According to their magnetic field structure, the 154 events were classified as magnetic cloud, non-cloud and complex ICMEs. The later one is refered to a magnetic clouds that are followed and/or preceded by another ICME. We discuss the differences and similarities of our results with those of previous studies. Supported by NSF/SHINE, NASA/LWS, and CONACyT. @-------------------------------------------------------------------- Title: Relative Timing of Coronal Mass Ejections, Flares and Type II Radio Bursts Authors: Rosas, A. M.; Gopalswamy, N.; Kaiser, M.; Yashiro, S.; Nunes, S. Bibliographic Code: 2004AGUSMSH41A..04R Abstract An investigation of 229 interplanetary type II radio bursts and the associated white-light coronal mass ejections (CMEs) is presented. The radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz (decameter-hectometric, DH) range, while the CMEs were observed by the Solar and Heliospheric Observatory (SOHO). The study period, 1997-2003, encompasses the current solar cycle (23) between minimum and beyond maximum. We could only find 144 solar flares associated with DH type IIs. We obtained the difference onset times (solar flare - DH type II) and found that DH type IIs onset is well after the flares. On the other hand the difference between CME and DH type II onset times indicates that the type II bursts occur well after the CME onset. The present study suggests that the CMEs are more likely to be the source of the shocks responsible for the type II bursts. We extended the study to metric type II bursts and found that they are after the CMEs and flares. A chronological order of these phenonmena is CME, flare, metric type II, and DH type II. Work supported by NASA/LWS and NSF/SHINE Programs @-------------------------------------------------------------------- Title: Coronal Mass Ejections observed by SOHO during the October-November 2003 Storms Authors: Gopalswamy, N.; Yashiro, S.; Vourlidas, A.; Lara, A.; Stenborg, G.; Kaiser, M.; Howard, R. Bibliographic Code: 2004AGUSMSH31B..03G Abstract Fast coronal mass ejections (CMEs), X-class flares, solar energetic particles, and interplanetary shocks were abundantly observed during the solar eruptions of October-November 2003. The Large Angle and Spectrometric Coronagraph (LASCO) on board SOHO detected more than five dozen CMEs from three active regions (NOAA ARs 0484, 0486, and 0488). We compare the statistical properties of these super-storm CMEs with those of the general population observed during cycle 23. We find that (i) the super-storm CMEs are faster and wider than average, and hence possess enormous energy, (ii) nearly 20 percent of the ultra-fast CMEs (speed > 2000 km/s) occurred during the October-November interval, including the fastest CME of cycle 23 (2700 km/s), and (iii) the rate of full-halo CMEs was nearly four times the average rate during cycle 23. We discuss the implications of these extreme properties for the solar energy source. We also discuss the interplanetary consequences of these CMEs, such as shocks, radio bursts and solar energetic particles. @-------------------------------------------------------------------- Title: Coronal Mass Ejections When the Sun Went Wild Authors: Gopalswamy, N.; Yashiro, S.; Vourlidas, A.; Lara, A.; Stenborg, G.; Kaiser, M. L.; Howard, R. A. Bibliographic Code: 2004AAS...204.4709G Abstract The Large Angle and Spectrometric Coronagraph (LASCO) on board SOHO detected more than five dozen CMEs from three active regions (NOAA ARs 0484, 0486, and 0488) during the October-November 2003 super storms. The CMEs were accompanied by X-class flares, solar energetic particles, and interplanetary shocks. We compare the statistical properties of these super-storm CMEs with those of the general population of CMEs observed during cycle 23. We find that (i) the super-storm CMEs are faster and wider than average, and hence possess enormous energy, (ii) nearly 20 percent of the ultra-fast CMEs (speed > 2000 km/s) occurred during the October-November interval, including the fastest CME of cycle 23 (2700 km/s), and (iii) the rate of full-halo CMEs was nearly four times the average rate during cycle 23. As expected, many of these CMEs were driving shocks near the Sun as inferred from the Wind/WAVES radio data and at least eight of them impacted Earth. These strong shocks accelerated solar energetic particles, which remained at hazardous levels for many days. We discuss the implications of these extreme properties of CMEs for the solar energy source. @-------------------------------------------------------------------- Title: Characteristic Periodicities in the Coronal Mass Ejection Production Authors: Lara, A.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2004AAS...204.3806L Abstract The solar activity is cyclic by nature, some periods of activity are obvious and well known and some are hidden, but all of them should be related to fundamental processes in the solar interior like the dynamo. The search for hidden periodicities, which can give us information about the solar activity causes, has been done for many years with different degrees of success. Almost all measurable solar parameters have been subject to a power spectral analysis and now there are some well known periodicities related to such parameters. On the other hand there are some events like Coronal Mass Ejections (CMEs) which, until recently, were difficult to observe routinely and then, we did not have a reliable database to perform a power spectrum analysis. Using the LASCO/SOHO CME list, which contains the information of the CME characteristics observed from 1996 to 2003, we have now a reliable time series of the CME production during 8 years covering the minimum, maximum and part of the declining phases of solar activity cycle 23, in this work we present preliminary results of the power spectral analysis of the CME activity. This work work was supported by NASA/LWS and NSF/SHINE (ATM 0204588) programs @-------------------------------------------------------------------- Title: Prominence eruptions and coronal mass ejection: a statistical study using microwave observations Authors: Gopalswamy, N.; Lu, W.; Yashiro, S.; Shimojo, M.; Shibasaki, K. Bibliographic Code: 2004naoj.book...18G Abstract @-------------------------------------------------------------------- Title: Coronal Mass Ejections and Galactic Cosmic Ray Modulation Authors: Lara, A.; Gopalswamy, N.; Caballero, R.; Yashiro, S. Bibliographic Code: 2004cosp...35.2926L Abstract We present a study of the long term evolution of Coronal Mass Ejections (CME) observed by LASCO/SOHO during the ascending, maximum and part of the descending phase of cycle 23 and its relation with the galactic cosmic ray (GCR) intensity modulation observed at one astronomical unit by Climax Neutron Monitor and IMP-8 spacecraft. We compare the long term GCR modulation with the CME production at low and high latitudes and CME parameters (width and speed). We found a very high (˜ 0.94) correlation between the number of high latitude CMEs and GCR during the ascending phase of solar cycle 23. @-------------------------------------------------------------------- Title: Composition and magnetic structure of interplanetary coronal mass ejections at 1 AU Authors: Aguilar-Rodriguez, E.; Blanco-Cano, X.; Gopalswamy, N. Bibliographic Code: 2004cosp...35.2411A Abstract We present a combined study of magnetic structure and charge state ratio of interplanetary coronal mass ejections (ICMEs) observed in interplanetary space by ACE and Wind spacecrafts. Measurements of abundances and charge state ratio of heavy ions (e.g. O⁺⁷/O⁺⁶, C⁺⁵/C⁺⁶, and Mg/O) in the solar wind as well as magnetic field structure are important tracers for physical conditions and processes in the source regions of the solar wind. We used ion composition (ACE), plasma (Wind) and magnetic field (Wind and ACE) data over a period of time from 1998 to 2002. Using the low proton temperature criterion, a common plasma signature of ICMEs, we identified 154 events which were classified as magnetic cloud, non-cloud and complex ICMEs. The later one is refered to the overtaking of succesive ICMEs which can include both magnetic clouds and non-cloud ejecta. We discuss the differences and similarities of our results with those of previous studies. Supported by NSF/SHINE, NASA/LWS, and CONACyT. @-------------------------------------------------------------------- Title: Plasma and magnetic field of the solar wind Authors: Gopalswamy, N. Bibliographic Code: 2004cosp...35.2396G Abstract Earth is always embedded in one of the three types of flows related to coronal mass ejections (CMEs), slow solar wind or fast solar wind. The topology of the magnetic field is different in the CME-related flows compared to the other two. I discuss the solar sources of the three types of flows. In particular, the relationship between CMEs in the solar wind and their solar counterparts will be explored to understand the possible reasons for the different number and speed distributions. Earth-directed CMEs constitute a special population of CMEs because they directly impact Earth. Earth-directed halo CMEs also seem to have properties different from the ordinary CMEs: their average speed is twice that of the general population. Finally, the solar cycle variation of the number of instances of CME-related flows at Earth will be compared with the occurrence rates of CMEs, solar energetic particle events, and interplanetary type II radio bursts produced by CME-driven shocks. @-------------------------------------------------------------------- Title: Coronal Mass Ejections and Solar Particle Events in Solar Cycle 23 Authors: Gopalswamy, N. Bibliographic Code: 2004cosp...35.2358G Abstract I provide an overview of the coronal mass ejection (CME) phenomenon as recorded primarily by the Solar and Heliospheric Observatory (SOHO) mission during the current solar activity cycle (23). After summarizing the statistical properties of CMEs and their solar-cycle variation, a discussion on the CME-associated activities will be presented. Particular emphasis will be placed on solar energetic particles (SEPs), which are related to CMEs that are faster and wider on average. Even though it is generally accepted that large SEP events are due to CME-driven shocks, the correlation between the two phenomena is less than perfect. Reasons for this poor correlation will be explored, including the influence of preceding CMEs. Fast and wide CMEs also produce long-wavelength radio bursts, so the connection between SEP events and radio bursts will be explored. Finally, I will discuss the implications of CMEs to the evolution of the global solar magnetic field and to the 22-year cosmic ray modulation cycle. @-------------------------------------------------------------------- Title: Estimation of solar wind speed within 20Rs of the Sun by using limb CMEs Authors: Nakagawa, T.; Gopalswamy, N.; Yashiro, S.; Matsuoka, A.; Nozomi/Mgf Team Bibliographic Code: 2004cosp...35.1632N Abstract The speeds of propagation of CMEs in interplanetary space are less distributed than their initial speeds measured on their departure from the limb of the Sun. Gopalswamy et al.(2000, 2001) presented a linear relationship between initial speeds of limb CMEs and their average acceleration during their travel time in interplanetary space. The linear relationship suggests that some dragging force is acting on CMEs, depending on difference in speed between the CME and their ambient plasmas. The ambient speed obtained from the coeficcients of the linear relationship was 406 km/s, which is nearly the same as the real solar wind speed. If similar relationship holds within 20 solar radii from the Sun, it would give information on the initial speed of 'ambient' solar wind in the vicinity of the Sun. The relationship between the initial acceleration and the initial speeds of limb CMEs was examined by using SOHO/LASCO CME Catalogue (http://cdaw.gsfc.nasa.gov/CME_list/). Coefficients of correlation between the initial acceleration and the initial speeds of low-latitude CMEs were calculated by sliding 27-day windows in 1999. Although there were many cases where linear relationship was not clear, we found significant number of periods for which correlation coefficient was fairly good (from -0.6 to -1). For such cases, the 'ambient' solar wind speed within 20 solar radii was estimated to be 150 - 570 km/s. It is somewhat slower than but close to the speeds of real solar wind measured in interplanetary space. It suggests that low-latitude solar wind plasma was accelerated within a short distance. It may also indicate that coronal holes are not the only source of the solar wind. The 'ambient' speeds thus obtained did not always agreed with simultaneous, in-situ measurements by NOZOMI and ACE. Estimation of 'ambient' speed was also carried out by using CMEs that appeared in higher latitude, but no latitudinal dependence was found. Acknowledgments:This CME catalog is generated and maintained by NASA and The Catholic University of America in cooperation with the Naval Research Laboratory. SOHO is a project of international cooperation between ESA and NASA. Reference: Gopalswamy et al., GRL, 27, p145, 2000. Gopalswamy et al., JGR, 106, p29207, 2001. @-------------------------------------------------------------------- Title: Variability of solar eruptions during cycle 23 Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. A. Bibliographic Code: 2004AdSpR..34..391G Abstract We report on the solar cycle variation of the rate of coronal mass ejections (CMEs), their mean and median speeds, and the rate of type II radio bursts. We found that both CME rate and speed (mean and median) increased from solar minimum to maximum by factors of 10 and 2, respectively. The CME rate during solar maximum is nearly twice the rates quoted previously. Large spikes in the speed variation were due to active regions that were highly active. The poor correlation between metric and DH type II bursts is confirmed, and the difference is attributed to the different Alfven speeds in the respective source regions. @-------------------------------------------------------------------- Title: On coronal streamer changes Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki, K.; Howard, R. A. Bibliographic Code: 2004AdSpR..33..676G Abstract Coronal streamer represents one of the pre-eruption configurations of coronal mass ejections (CMEs), because they overlie prominences and often possess all the substructures of CMEs. In this paper, we report on a study of streamer changes associated with prominence eruptions. The prominence eruptions and streamer changes were observed by the Nobeyama radioheliograph and Solar and Heliospheric Observatory (SOHO), respectively. Multiwavelength data showed that at least one of the streamer events involved heating and small-scale material ejection that subsequently stalled. After presenting illustrative examples, we compare the properties of the streamer-related events with those of general population of prominence events. We find that the properties of streamer-related prominence events are closer to those of prominence eruptions with transverse trajectories. @-------------------------------------------------------------------- Title: Merged interaction regions at 1 AU Authors: Burlaga, L.; Berdichevsky, D.; Gopalswamy, N.; Lepping, R.; Zurbuchen, T. Bibliographic Code: 2003JGRA..108.1425B Abstract We discuss the existence of large, complex merged interaction regions (MIRs) in the solar wind near Earth. MIRs can have configurations that cause more prolonged geomagnetic effects than a single flow structure. A MIR or successive MIRs can produce relatively long lasting Forbush decreases at 1 AU. We illustrate MIRs at 1 AU with two examples (MIR-1 and MIR-2) seen by WIND and ACE in the interval from 18 March through 29 March 2002. We determined the probable structure and origin of each in terms of interacting flows and shocks using in situ and solar observations, but we emphasize that there are uncertainties that cannot be resolved with these data alone. The MIRs were relatively large structures with radial extent ~2/3 and 3/4 AU, respectively. MIR-1 was formed by interactions related to at least two complex ejecta, a magnetic cloud, and two shocks. MIR-2 was related to a corotating stream, the heliospheric plasma sheet (HPS), two complex ejecta, a magnetic cloud and at least two shocks. A MIR can evolve significantly while it moves to 1 AU, and memory of the conditions near the Sun is lost in the process. Thus one cannot unambiguously determine the structure of a MIR and the manner in which it formed using observations from a single spacecraft at 1 AU. The magnetic field strength profiles in MIRs are not correlated with the speed and density profiles so that one cannot infer the magnetic field strength in MIRs from remote sensing observation that give density and speed information. It will be possible to better understand the dynamical processes leading to the formation of MIRs with remote sensing observations, but they cannot measure the magnetic fields in MIRs. @-------------------------------------------------------------------- Title: Comment on ``Coronal mass ejections, interplanetary ejecta and geomagnetic storms'' by H. V. Cane, I. G. Richardson, and O. C. St. Cyr Authors: Gopalswamy, N.; Manoharan, P. K.; Yashiro, S. Bibliographic Code: 2003GeoRL..30xSSC1G Abstract Abstract Available from AGU @-------------------------------------------------------------------- Title: Key Issues Related to Solar Sources and Interplanetary Propagation of the April 2002 Events Authors: Gopalswamy, N. Bibliographic Code: 2003AGUFMSM41A..02G Abstract A summary of the solar events such as coronal mass ejections (CMEs) and flares associated with the April 2002 storms will be provided. In particular events from the primary active region, AR9906 and the underlying magnetic configuration will be discussed. The connection of these CMEs to the interplanetary shocks and the solar energetic particles events will be explored. Based on the arrival times of the interplanetary CMEs and shocks, the evolution of these disturbances as they propagated between the Sun and Earth will be described. Finally, a comparison of the April 2002 events with other geoeffective events will be made. @-------------------------------------------------------------------- Title: Radio Coverage from Chromosphere to Earth: FASR-LOFAR-SIRA Synergy Authors: Gary, D. E.; Kassim, N.; Gopalswamy, N.; Aschwanden, M. J. Bibliographic Code: 2003AGUFMSH42E..02G Abstract Radio emission is uniquely sensitive to a number of key plasma parameters (magnetic field, temperature, density, high-energy electrons, and various plasma waves) over heights ranging without gaps from the chromosphere, throughout the corona and heliosphere, to the Earth. Two ground-based radio arrays, the Frequency Agile Solar Radiotelescope (FASR) and the Low Frequency Array (LOFAR), together with the space-based Solar Imaging Radio Array (SIRA) are planned that will for the first time provide direct imaging of disturbances over this vast height range through interferometric imaging over their equally impressive frequency range of 24 GHz to 30 kHz. We describe the science goals of these instruments, focusing especially on the science addressed jointly by all three instruments. Among the examples are (1) simultaneous imaging of CMEs, flaring loops, and shock-associated (type II) emission and (2) imaging the propagation of electrons on open field lines (type III), from their acceleration point through the corona and heliosphere to the point where they are measured in situ by near-Earth spacecraft. In addition to spatially relating the different phenomena, the spectral information is rich in quantitative diagnostics. We give some examples of the revolutionary results we can expect from the combined instruments. @-------------------------------------------------------------------- Title: Coronal Mass Ejections, Flares and Type II Radio Bursts Authors: Rosas, A. M.; Gopalswamy, N.; Kaiser, M. L.; Yahsiro, S.; Nunes, S. Bibliographic Code: 2003AGUFMSH42C0559R Abstract An investigation of 210 interplanetary type II radio bursts and the associated white-light coronal mass ejections (CMEs) is presented. The radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz (decameter-hectometric, DH) range, while the CMEs were observed by the Solar and Heliospheric Observatory (SOHO). The study period, 1997-2002, encompasses the current solar cycle (23) between minimum and beyond maximum. We could only find 108 solar flares associated with DH type IIs. We obtained the difference onset times (solar flare - DH type II) and found that DH type IIs start at the same time as the flares. On the other hand the difference between CME and DH type II onset times is indicates that the type II bursts occur well after the CME onset. The present study suggests that the CMEs are more likely to be the source of the shocks responsible for the type II bursts. We extend the study to metric type II bursts and obtained similar results. @-------------------------------------------------------------------- Title: Type II Radio Bursts and Energetic Solar Eruptions Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. A.; Kaiser, M. L. Bibliographic Code: 2003AGUFMSH42C0556G Abstract Type II radio bursts at decameter-hectometric (DH) and kilometric wavelengths are indicative of CME-driven shocks in the interplanetary medium. Only a subset of these type II bursts continue from the DH to the km regimes. We report on a study of these long-lasting type II bursts using data from the Wind/WAVES experiment in conjunction with white-light coronal mass ejection (CME) data from SOHO. We find the majority of these events (80 percent) are also associated with metric Type II bursts. We also studied the properties of the associated CMEs and found them to be the most energetic when compared to CMEs associated with bursts in any single wavelength regime. @-------------------------------------------------------------------- Title: Probing Solar Energetic Particles with SIRA Authors: Aschwanden, M. J.; Nitta, N.; Lemaster, E.; Byler, E.; Gary, D.; Kassim, N.; Gopalswamy, N. Bibliographic Code: 2003AGUFMSH42C0555A Abstract The space-based SIRA (Solar Imaging Radio Array) will provide a powerful capability to track high energy particles from solar flare and CME sites through interplanetary/heliospheric space all the way to Earth. Together with two other overlapping planned radio interferometers, i.e., FASR (Frequency-Agile Solar Radiotelescope) and LOFAR (Low-Frequency Array) the entire plasma frequency range from 30 GHz all the way down to the plasma frequency cutoff of 30 kHz at 1 AU will be covered. These instruments will track the magnetic trajectory of high energy particles, beam-driven radio emission, and localize the acceleration sites in the corona or interplanetary shocks. We simulate some CME and type III events, as they will be mapped with these instruments, using realistic scattering functions of radio waves on coronal and heliospheric density inhomogeneities. @-------------------------------------------------------------------- Title: Coronal Mass Ejections and Solar Polarity Reversal Authors: Gopalswamy, N.; Lara, A.; Yashiro, S.; Howard, R. A. Bibliographic Code: 2003ApJ...598L..63G Abstract We report on a close relationship between the solar polarity reversal and the cessation of high-latitude coronal mass ejections (CMEs). This result holds good for individual poles of the Sun for cycles 21 and 23, for which CME data are available. The high-latitude CMEs provide a natural explanation for the disappearance of the polar crown filaments (PCFs) that rush the poles. The PCFs, which are closed field structures, need to be removed before the poles could acquire open field structure of the opposite polarity. Inclusion of CMEs along with the photospheric and subphotospheric processes completes the full set of phenomena to be explained by any solar dynamo theory. @-------------------------------------------------------------------- Title: Dynamics of coronal mass ejections in the near-Sun interplanetary space Authors: Vrsnak, B.; Ruzdajak, D.; Sudar, D.; Gopalswamy, N. Bibliographic Code: 2003ESASP.535..517V Abstract Kinematics of more than 5000 coronal mass ejections (CMEs) measured between 2 and 30 solar radii is investigated. A distinct relationship between the late-phase acceleration of CMEs and their velocities is found. It can be represented in the form a_{[m s^-2]} = -0.02(v-400)_{[km s^-1]}. The relationship is interpreted in terms of coupling of the CME motion and the solar wind, i.e., by the action of the aerodynamic drag. The results indicate that in the considered radial distance range the Lorentz force acceleration becomes weak, in the majority of the events spanning between 0 and 10 m s^-2. Implications for the interplanetary motion of CMEs are discussed, emphasising the prediction of the 1 a.u. arrival time. @-------------------------------------------------------------------- Title: Variations of magnetic clouds and CMEs with solar activity cycle Authors: Wu, Chin-Chun; Lepping, R. P.; Gopalswamy, N. Bibliographic Code: 2003ESASP.535..429W Abstract Sixty-eight magnetic clouds were observed by Wind during November 1994 - May 2002. The average occurrence rate is ~9 magnetic clouds per year for the overall period (68 events/7.6 years). It is found that some of the frequency of occurrence anomalies were during the early part of solar cycle 23: (I) only 4 clouds were observed in 1999, (II) an unusually large number of clouds (16 events) were observed in 1997 in which the Sun was starting to leave solar minimum. During the period of 1996-2001, the results also show: (1) the occurrence frequency of magnetic cloud appears to be related neither to the occurrence of solar coronal mass ejections (CMEs) as observed by SOHO nor to solar activity cycle, (2) the intensity of geomagnetic storms related to magnetic clouds is affected by both solar activity and the occurrence frequency of CMEs, and (3) ~91% of magnetic clouds induced geomagnetic storms. @-------------------------------------------------------------------- Title: Coronal mass ejection activity during solar cycle 23 Authors: Gopalswamy, Nat; Lara, Alejandro; Yashiro, Seiji; Nunes, Steven; Howard, Russell A. Bibliographic Code: 2003ESASP.535..403G Abstract We studied the solar cycle varition of various properties of coronal mass ejections (CMEs), such as daily CME rate, mean and median speeds, and the latitude of solar sources for cycle 23 (1996-2002). We find that (1) there is an order of magnitude increase in CME rate from the solar minimum (0.5/day) to maximum (6/day), (2) the maximum rate is significantly higher than previous estimates, (3) the mean and median speeds of CMEs also increase from minimum to maximum by a factor of 2, (4) the number of metric type II bursts (summed over CR) tracks CME rate, but the CME speed seems to be only of secondary importance, (5) for type II bursts originating farther from the Sun the CME speed is important, (6) the latitude distribution of CMEs separate the prominence-associated (high-latitude) and active-region associated CMEs, and (7) the rate of high-latitude CMEs shows north-south asymmetry and the cessation eruptions in the north and south roughly mark the polarity reversals. We compared the rates of the fast-and-wide CMEs, major solar flares, interplanetary (IP) shocks, long-wavelength type II bursts and large SEP events. This comparison revealed that the number of major flares is generally too large compared to all the other numbers. In other words, fast-and-wide CMEs, long-wavelength type II bursts, large SEP events, and IP shocks have a close physical relationship. @-------------------------------------------------------------------- Title: Effect of CME Interactions on the Production of Solar Energetic Particles Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.; Howard, R. A.; Leske, R.; von Rosenvinge, T.; Reames, D. V. Bibliographic Code: 2003AIPC..679..608G Abstract We analyzed a set of 52 fast and wide, frontside western hemispheric (FWFW) CMEs in conjunction with solar energetic particle (SEP) and radio burst data and found that 42 of these CMEs were associated with SEPs. All but two of the 42 SEP-associated FWFW CMEs (95%) were interacting with preceding CMEs or dense streamers. Most of the remaining 10 SEP-poor FWFW CMEs had either insignificant or no interaction with preceding CMEs or streamers, and were ejected into a tenuous corona. There is also a close association between type II radio bursts in the near-Sun interplanetary medium and SEP-associated FWFW CMEs suggesting that electron accelerators are also good proton accelerators. @-------------------------------------------------------------------- Title: A Numerical Study on the Evolution of CMEs and Shocks in the Interplanetary Medium Authors: González-Esparza, J. A.; Lara, A.; Santillán, A.; Gopalswamy, N. Bibliographic Code: 2003AIPC..679..206G Abstract We studied the evolution in the solar wind of four CMEs detected by SOHO-LASCO which were associated with ICMEs and interplanetary (IP) shocks detected afterward by Wind at 1 AU. The study is based on a 1-D hydrodynamic single fluid model using the ZEUS code. These simple numerical simulations of CME like pulses illuminate several aspects of the heliocentric evolution of the ICME front and its associated IP shock and we were able to reproduce some characteristics of the IP shocks and ICMEs inferred from the two-point measurements from spacecraft. The simulation shows that ICMEs and IP shocks follow different evolutions in the interplanetary medium both having phases of about constant speed propagation followed by an exponential deceleration with heliocentric distance. IP shocks always propagate faster than their associated ICME drivers and the former began to decelerate well before the IP shock. The results indicate that, in general, although an IP shock is driven by its ICME in the inner heliosphere in most of the cases this is not true any more when they approach to 1 AU. @-------------------------------------------------------------------- Title: Coronal and Interplanetary Environment of Large Solar Energetic Particle Events Authors: Gopalswamy, Nat; Yashiro, S.; Stenborg, G.; Howard, R. A. Bibliographic Code: 2003ICRC....6.3549G Abstract We studied the properties of coronal mass ejections (CMEs) associated with large solar energetic particle (SEP) events during 1997-2002 and compared them with those of preceding CMEs from the same source region. The primary findings of this study are (1) High-intensity (> 50 protons cm-2 s-1 sr-1 ) events are more likely to be preceded by other wide CMEs. (2) The preceding CMEs are faster and wider than average CMEs. (3) The primary CMEs often propagate through the near-Sun interplanetary medium severely disturb ed and distorted by the preceding CMEs. @-------------------------------------------------------------------- Title: Solar and geospace connections of energetic particle events Authors: Gopalswamy, N. Bibliographic Code: 2003GeoRL..30lSEP1G Abstract A Coordinated Data Analysis Workshop (CDAW) was conducted recently to study the solar and geospace connections of large solar energetic particle (SEP) events of solar cycle 23 (up to the end of 2001). This paper summarizes the properties these events, the scientific issues discussed, and some of the results obtained during the workshop. @-------------------------------------------------------------------- Title: Why was there no Solar Energetic Particle Event Associated with the Gamma-ray-line Flare of 2002 July 23? Authors: Gopalswamy, N.; Dennis, B. R.; Kaiser, M. L.; Krucker, S.; Lin, R. P.; Vourlidas, A. Bibliographic Code: 2003SPD....34.2202G Abstract We investigated the coronal and interplanetary (IP) events associated with two X-class flares on 2002 July 20 and 23. Both flares were associated with ultra-fast (>2000 km s^-1) coronal mass ejections (CMEs) and IP shocks. We use white-light, EUV, hard X-ray and radio observations to trace the origin of the CMEs to active region 0039 located close to the east limb. The July 20 flare was partly occulted by the east limb, yet it resulted in a major solar energetic particle event with intensity ˜ 20 pfu in the >10 MeV channel (1 pfu = 1 particle per (cm² s sr MeV)). The July 23 event was the first gamma-ray-line flare detected by RHESSI, but it did not show any enhancement in SEPs above the elevated background from the July 20 event. We identified two distinguishing factors between the July 2 and July 23 CMEs: (1) The July 20 CME had a higher kinetic energy, and (2) The July 20 CME was interacting with another fast CME (1350 km s^-1) that preceded by less than an hour from the same region; there were also two other CMEs on July 19 from the same region. Thus the coronal and IP environment of the July 20 event was highly disturbed due to preceding CMEs (as compared to the July 23 event). We suggest that the different coronal/IP environments may be responsible for the lack of SEP event associated with the July 23 event. @-------------------------------------------------------------------- Title: Solar Imaging Radio Array (SIRA): Radio Aperture Synthesis from Space Authors: MacDowall, R.; Kaiser, M.; Gopalswamy, N. Bibliographic Code: 2003SPD....34.2022M Abstract SIRA, the Solar Imaging Radio Array, will be a constellation of about 16 microsats designed to image radio sources in the solar corona and heliosphere using aperture synthesis techniques. These images will permit the mapping and tracking of CME-driven shocks (type II radio bursts) and solar flare electrons (type III radio bursts) as a function of time from near the sun to 1 AU. Two dimensional imaging of the CME-driven shock front is important for determination of space weather effects of CMEs, whereas imaging of the ubiquitous type III bursts will permit the derivation of density maps in the outer corona and solar wind. This will be the first mission to image the heliosphere (and the celestial sphere) with good angular resolution at frequencies below the ionospheric cutoff ( 10 MHz). The radio images are intrinsically complementary to white-light coronograph data, such as those of SDO, and can play a valuable role in the NASA Living with a Star program. @-------------------------------------------------------------------- Title: Influence of CME interaction on the Propagation of Interplanetary Shocks Authors: Manoharan, P. K.; Gopalswamy, N.; Yashiro, S.; Howard, R. A. Bibliographic Code: 2003SPD....34.0610M Abstract We studied a large number of coronal mass ejections (CMEs) and their associated interplanetary (IP) shocks for the period 1996-2002, using white-light images from the Large Angle and Spectrometric Coronagraph (LASCO) on the Solar Heliospheric Observatory (SOHO) spacecraft and solar wind measurements from the Mass Time-of-Flight spectrometer (MTOF on SOHO) and Solar Wind Experiment (SWE on the WIND satellite) instrument. The 1-AU arrival times of the CME and its shock are obtained from the initial CME speed. We studied the influence of preceding CMEs on the propagation of the IP shocks. We note that the propagation characteristics of some of the fast CMEs and their shocks are modified by the interaction with the preceding CMEs. We also find that the arrival times of IP shocks show deviation from that of non-interacting cases. We use an empirical model to explain the change in the travel time of shocks. We also discuss other consequences in the solar wind caused by the CME interactions. This work is supported by NASA living with a Star, NSF/SHINE (ATM 0204588), and AFOSR Programs. @-------------------------------------------------------------------- Title: Long Lasting Type II Radio Bursts Authors: Nunes, S.; Gopalswamy, N.; Yashiro, S.; Howard, R. Bibliographic Code: 2003SPD....34.0607N Abstract Plasma frequencies starting in the decameter-hectametric (DH) regime and continuing into the kilometric (km) regime correspond to approximately to the entire Sun-Earth distance. Accordingly, we consider Type II radio bursts observed by the WAVES experiment on the WIND spacecraft that are observed from the DH to the km regimes and their association with white-light coronal mass ejections (CMEs). We find that approximately 80% of these events are associated with metric Type II bursts observed on Earth. We also consider correlations of DH/km Type II's with sunspot numbers and other cyclical measures of solar activity, and properties of CMEs associated with DH/km Type II bursts. This work is supported by the Air Force Office of Scientific Research, the National Science Foundation's SHINE Program, and NASA. @-------------------------------------------------------------------- Title: Analysis of Onset Times between CMEs and Associated DH Type II Bursts Authors: Rosas, A. M.; Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. L. Bibliographic Code: 2003SPD....34.0506R Abstract An investigation of 210 interplanetary type II radio bursts and the associated white-light coronal mass ejections (CMEs) is presented.The radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz (decameter-hectometric,DH) range, while the CMEs were observed by the Solar and Heliospheric Observatory (SOHO).The study period, 1997-2002, encompasses the current solar cycle (23) between minimum and beyond maximum. We find that 91% of CMEs have speeds greater than 450 km/s and 94% have angular widths greater than 60 degrees obtained from SOHO/LASCO C2 and C3 CME measurements.We made a linear and quadratic fit using CME height time measurements to extrapolate CME onset times to 2 and 1 solar radius. We find that the quadratic onset times (QOTs) illustrates less scatter in the difference times (CME onset time - DH onset time) than the linear onset times (LOTs). Both the QOT and LOT for 1 solar radius shows that ˜ 80% DH type II bursts occurred within 1 hour of CME onset time and for 2 solar radius extrapolation shows ˜ 87%. Correlation coefficients were found to be very weak between difference times and CME longitude, speed, angular width, and DH type II starting frequency. We are continuing to investigate the outlier (DH type II bursts occurring more than 2 hours after CMEs) events.(1) The onset times and starting frequency of DH type IIs with respect to CME onset times provides insight into the coronal density distribution.(2) The relationship between CME onset time and the occurrence of the DH type II will be discussed in terms of the radial distribution of the Alfven speed near the Sun. This work is supported by NASA living with a Star and NSF/SHINE (ATM 0204588) and AFOSR Programs. @-------------------------------------------------------------------- Title: Towards Automatic Tracking of Coronal Mass Ejections Authors: Stenborg, G. A.; Cobelli, P. J.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2003SPD....34.0306S Abstract Tracing identifiable features of dynamical phenomena such as coronal mass ejections (CMEs), as they propagate through the corona, is a real challenge. In particular, different features from a single event usually display different velocities. Moreover, the lack of sharpness of the structures involved on top of the subjective nature of the measuring process makes it difficult to track the event unambiguously. To overcome the lack of sharpness, we developed a multiresolution image processing technique applicable to any 2D data set to enhance both boundaries and internal details of originally faint and diffuse structures. The method implemented employs a multi-level decomposition scheme (splitting algorithm of a wavelet packet on non-orthogonal wavelets) via the `a trous' wavelet transform, local noise reduction and interactive weighted recomposition. This approach represents a major advance towards unambiguous image interpretation and provides a means for the quantification of stationary and dynamic coronal structures required for conducting morphological studies. Moreover, it proved to be a necessary step in the development of a non-subjective technique for automatic tracking of CMEs. Examples based on LASCO-C1, -C2, -C3, and EIT data sets are shown. Different reconstruction strategies are also discussed. This work is supported by NASA living with a Star and NSF/SHINE (ATM 0204588) Programs. @-------------------------------------------------------------------- Title: A statistical study of CMEs associated with metric type II bursts Authors: Lara, A.; Gopalswamy, N.; Nunes, S.; Muñoz, G.; Yashiro, S. Bibliographic Code: 2003GeoRL..30lSEP4L Abstract We present a statistical study of the characteristics of CMEs which show temporal association with type II bursts in the metric domain but not in the decameter/hectometric (DH) domain. This study is based on a set of 80 metric (m) type II bursts associated with surface events in the solar western hemisphere. It was found that in general, the distribution of the widths and speeds of the CMEs associated with metric (but not DH) type II bursts are shifted towards higher values compared to those of all CMEs observed by LASCO in the 1996-2001 period. We also found that these distributions have lower values than the same distributions of the CMEs associated with DH type II bursts. In terms of energy, this means that the CMEs associated only with metric type II bursts are more energetic (wider and faster) than regular CMEs but less energetic than the CMEs associated with DH type II bursts. @-------------------------------------------------------------------- Title: Large solar energetic particle events of cycle 23: A global view Authors: Gopalswamy, N.; Yashiro, S.; Lara, A.; Kaiser, M. L.; Thompson, B. J.; Gallagher, P. T.; Howard, R. A. Bibliographic Code: 2003GeoRL..30lSEP3G Abstract We report on a study of all the large solar energetic particle (SEP) events that occurred during the minimum to maximum interval of solar cycle 23. The main results are: 1. The occurrence rate of the SEP events, long-wavelength type II bursts and the fast and wide frontside western hemispheric CMEs is quite similar, consistent with the scenario that CME-driven shocks accelerate both protons and electrons; major flares have a much higher rate. 2. The SEP intensity is better correlated with the CME speed than with the X-ray flare class. 3. CMEs associated with high-intensity SEPs are about 4 times more likely to be preceded by wide CMEs from the same solar source region, suggesting the importance of the preconditioning of the eruption region. We use a specific event to demonstrate that preceding eruption from a nearby source can significantly affect the properties of SEPs and type II radio bursts. @-------------------------------------------------------------------- Title: The Solar Radio Imaging Array (SIRA) microsatellite mission Authors: MacDowall, R.; Gopalswamy, N.; Kaiser, M. Bibliographic Code: 2003EAEJA....12917M Abstract SIRA, the Solar Imaging Radio Array, will be a constellation of about 16 microsats designed to image radio sources in the solar corona and heliosphere using aperture synthesis techniques. These images will permit the mapping and tracking of CME-driven shocks (type II radio bursts) and solar flare electrons (type III radio bursts) as a function of time from near the sun to 1 AU. Two dimensional imaging of the CME-driven shock front is important for determination of space weather effects of CMEs, whereas imaging of the ubiquitous type III bursts will permit the derivation of density maps in the outer corona and solar wind. This will be the first mission to image the heliosphere (and the celestial sphere) with good angular resolution at frequencies below the ionospheric cutoff (~10 MHz). In this presentation, we highlight the ways in which SIRA is complementary to LOFAR and FASR. @-------------------------------------------------------------------- Title: Low frequency radio astronomy from space: the Solar Radio Imaging Array Authors: MacDowall, R.; Gopalswamy, N.; Kaiser, M. Bibliographic Code: 2003EAEJA....12863M Abstract SIRA, the Solar Imaging Radio Array, will be a constellation of about 16 microsats designed to image radio sources in the solar corona and heliosphere using aperture synthesis techniques. Using crossed dipoles and high dynamic range radio receivers, SIRA will observe solar radio emissions in the frequency range from ~15 MHz to ~30 kHz. These frequencies correspond to distances of 2 R_sun to 1 AU. Frequency spacing and time resolution will be optimized for solar burst analysis. The quasi-spherical constellation (diameter 25-50 km) will provide appropriate baselines for angular resolution of ~10 arcsec at 15 MHz. Several orbit possibilities are currently under consideration. Rapid data processing for space weather prediction of CME arrival at 1 AU is a major goal. It is anticipated that this mission will be proposed for the next NASA MIDEX opportunity. @-------------------------------------------------------------------- Title: A Statistical Study of CMEs Associated with Metric Type II bursts Authors: Lara, A.; Gopalswamy, N.; Nunes, S.; Munoz, G.; Yashiro, S. Bibliographic Code: 2003EAEJA....11532L Abstract We present a statistical study of the characteristics of CMEs which show temporal association with type II burst in the metric domain but not in the decameter/hectometric (DH) domain. This study is based on a set of 80 metric (m) type II bursts associated with surface events in the solar western hemisphere. It was found that in general, the distribution of the widths and speeds of the CMEs associated with metric (but not DH) type II bursts are shifted towards higher values compared to those of all CMEs observed by LASCO in the 1996-2001 period. We also found that these distributions have lower values than the same distributions of the CMEs associated with DH type II bursts. In terms of energy, this means that the CMEs associated only with metric type II bursts are more energetic (wider and faster) than regular CMEs but less energetic than the CMEs associated with DH type II bursts. @-------------------------------------------------------------------- Title: Coordinated Data Analysis Workshops Authors: Gopalswamy, N.; Thompson, B. J.; Zarro, D.; Dimitoglou, G. Bibliographic Code: 2003EAEJA.....4585G Abstract The concept of Coordinated Data Analysis Workshops (CDAWs) have proved to be extremely successful in bringing together data and people with various expertise/instrument background to attack selected problems. Typical preparation for the CDAW consists of identifying relevant data from a wide variety of sources (solar, interplanetary, magnetospheric and climatary), accumulating the data and gathering the software tools. Participants in the workshop are expected to do a lot of "preprocessing" and deposit their data or models prior to arriving at the workshop, which will be jointly analyzed to produce scientific results. Additional conferences may be scheduled at a later date, which will allow a venue for scientific talks on the CDAW results and associated science. In this paper, we summarize the evolution of CDAW activities in the recent past and how this experience may be beneficial for the activities associated with the International Heliophysical Year. @-------------------------------------------------------------------- Title: Recent advances in long-wavelength radio physics of the Sun Authors: Gopalswamy, N. Bibliographic Code: 2003EAEJA.....4473G Abstract Low frequency imaging of the solar radio bursts provides the best means of studying the solar disturbances such as coronal mass ejections and shocks at the moment of their departure from the Sun. The radio bursts also provide information on the physical properties of the medium such as the density, temperature and magnetic field. Direct imaging of the quiet Sun also provides information on the outer corona. I review some of the results obtained from recent long-wavelength observations and summarize the relevance of these results to LOFAR. In addition, I discuss the significance of LOFAR to future low frequency imaging observations from space such as the Solar Imaging Radio Array (SIRA). @-------------------------------------------------------------------- Title: Coronal mass ejections as a source of space Weather Authors: Gopalswamy, N. Bibliographic Code: 2003EAEJA.....4456G Abstract White-light and radio observations of solar eruptions obtained by SOHO and Wind, respectively have helped us understand the space weather aspect of coronal mass ejections (CMEs). From space weather point of CMEs are important in two respects: (1) CMEs departing from close to the disk center are important for producing geomagnetic storms, so it is important to understand how they evolve and when they arrive at the earth, (2) Fast and wide CMEs drive shocks and hence accelerate solar energetic particles detected in situ or via the long wavelength type II radio bursts. The SEP-associated CMEs can depart from the Sun from any longitude, but western events are more geoeffective. Recent results show that only 1-2 percent of all CMEs are important for space weather purposes. In this paper, we review the recent results obtained on these two populations of CMEs in comparison with the general population. @-------------------------------------------------------------------- Title: Prominence Eruptions and Coronal Mass Ejection: A Statistical Study Using Microwave Observations Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki, K.; Howard, R. A. Bibliographic Code: 2003ApJ...586..562G Abstract We present the results of a statistical study of a large number of solar prominence events (PEs) observed by the Nobeyama Radioheliograph. We studied the association rate, relative timing, and spatial correspondence between PEs and coronal mass ejections (CMEs). We classified the PEs as radial and transverse, depending on whether the prominence moved predominantly in the radial or horizontal direction. The radial events were faster and attained a larger height above the solar surface than the transverse events. Out of the 186 events studied, 152 (82%) were radial events, while only 34 (18%) were transverse events. Comparison with white-light CME data revealed that 134 (72%) PEs were clearly associated with CMEs. We compare our results with those of other studies involving PEs and white-light CMEs in order to address the controversy in the rate of association between CMEs and prominence eruptions. We also studied the temporal and spatial relationship between prominence and CME events. The CMEs and PEs seem to start roughly at the same time. There was no solar cycle dependence of the temporal relationship. The spatial relationship was, however, solar cycle dependent. During the solar minimum, the central position angle of the CMEs had a tendency to be offset closer to the equator as compared to that of the PE, while no such effect was seen during solar maximum. @-------------------------------------------------------------------- Title: A New Method for Estimating Widths, Velocities, and Source Location of Halo Coronal Mass Ejections Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2003ApJ...584..472M, eprint = 0710.4524 Abstract It is well known that coronagraphic observations of halo coronal mass ejections (CMEs) are subject to projection effects. Viewing in the plane of the sky does not allow us to determine the crucial parameters that define the geoeffectiveness of CMEs, such as the space speed, width, or source location. Assuming that halo CMEs have constant velocities, are symmetric, and propagate with constant angular widths, at least in their early phase, we have developed a technique that allows us to obtain the required parameters. This technique requires measurements of sky-plane speeds and the moments of the first appearance of the halo CMEs above opposite limbs. We apply this technique to obtain the parameters of all the halo CMEs observed by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph experiment until the end of 2000. We also present a statistical summary of these derived parameters of the halo CMEs. @-------------------------------------------------------------------- Title: A numerical study on the acceleration and transit time of coronal mass ejections in the interplanetary medium Authors: González-Esparza, J. Américo; Lara, Alejandro; Pérez-Tijerina, Eduardo; Santillán, Alfredo; Gopalswamy, Nat Bibliographic Code: 2003JGRA..108.1039G Abstract Recently, an empirical model of the acceleration/deceleration of coronal mass ejections (CMEs) as they propagate through the solar wind was developed using near-Sun (coronagraphic) and near-Earth (in situ) observations [Gopalswamy et al., 2000, 2001a]. This model states and quantifies the fact that slow CMEs are accelerated and fast CMEs are decelerated toward the ambient solar wind speed (~400 km/s). In this work we study the propagation of CMEs from near the Sun (0.083 AU) to 1 AU using numerical simulations and compare the results with those of the empirical model. This is a parametric study of CME-like disturbances in the solar wind using a one-dimensional, hydrodynamic single-fluid model. Simulated CMEs are propagated through a variable ambient solar wind and their 1 AU characteristics are derived to compare with observations and the empirical CME arrival model. We were able to reproduce the general characteristics of the prediction model and to obtain reasonable agreement with two-point measurements from spacecraft. Our results also show that the dynamical evolution of fast CMEs has three phases: (1) an abrupt and strong deceleration just after their injection against the ambient wind, which ceases before 0.1 AU, followed by (2) a constant speed propagation until about 0.45 AU, and, finally, (3) a gradual and small deceleration that continues beyond 1 AU. The results show that it is somewhat difficult to predict the arrival time of slow CMEs (V_cme < 400 km/s) probably because the travel time depends not only on the CME initial speed but also on the characteristics of the ambient solar wind and CMEs. However, the simulations show that the arrival time of very fast CMEs (V_cme > 1000 km/s) has a smaller dispersion so the prediction can be more accurate. @-------------------------------------------------------------------- Title: Properties of narrow coronal mass ejections observed with LASCO Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; Howard, R. A. Bibliographic Code: 2003AdSpR..32.2631Y Abstract We report the statistical properties of narrow coronal mass ejections (CMEs, angular width < 20°) withparticular emphasis on comparison with normal CMEs. We investigated 806 narrow CMEs from an online LASCO/CME catalog and found that (1) the fraction of narrow CMEs increases from 12% to 22% towards solar maximum, (2) during the solar maximum, the narrow CMEs are generally faster than normal ones, (3) the maximum speed of narrow CMEs (1141 km s^-1) is much smaller than that of the normal CMEs (2604 km s^-1). These results imply that narrow CMEs do not form a subset of normal CMEs and have a different acceleration mechanism from normal CMEs. @-------------------------------------------------------------------- Title: Coronal mass ejection interaction and particle acceleration during the 2001 April 14 15 events Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A. Bibliographic Code: 2003AdSpR..32.2613G Abstract Two successive solar energetic particle (SEP) events associated with fast and wide coronal mass ejections (CMEs) on 2001 April 14 and 15 are compared. The weak SEP event of April 14 associated with an 830 km/s CME and an M1.0 flare was the largest impulsive event of cycle 23. The April 15 event, the largest ground level event of cycle 23, was three orders of magnitude more intense than the April 14^th event and was associated with a faster CME (1200 km/s) and an X14.4 flare. We compiled and compared all the activities (flares, CMEs, interplanetary conditions and radio bursts) associated with the two SEP events to understand the intensity difference between them. Different coronal and interplanetary environments of the two events (presence of preceding CME and seed particles ahead of the April 15 event) may explain the intensity difference. @-------------------------------------------------------------------- Title: Coronal mass ejections: Initiation and detection Authors: Gopalswamy, N. Bibliographic Code: 2003AdSpR..31..869G Abstract Coronal mass ejections (CMEs) are large-scale magnetic structures expelled from the Sun due to MHD processes involving interaction between plasma and magnetic field in closed field regions. I provide a summary of the observational signatures and current models on CME initiation. I also discuss the multiwavelength signatures of CMEs, which have helped us obtain a global picture of the CME phenomenon in the inner heliosphere. @-------------------------------------------------------------------- Title: Arrival time of coronal mass ejections Authors: Michalek, G.; Gopalswamy, N.; Chane, E. Bibliographic Code: 2002ESASP.506..177M Abstract Halo coronal mass ejections (CMEs), originating near the disk center, cause the severest geomagnetic storms. Thus, estimation of the arrival of magnetic clouds in the Earth vicinity is very important in space weather investigation. We describe an empirical model to predict the 1 AU arrival time of CMEs. This model is based on the effective acceleration described by Gopalswamy et. al (2000). It was improved by considering halo CMEs for which the space velocities are determined. This allowed us to receive the more accurate estimations. The new model reduces the average prediction error from ≈10 to ≈5 hours. @-------------------------------------------------------------------- Title: A Statistical Study of Two Classes of Coronal Mass Ejections Authors: Moon, Y.-J.; Choe, G. S.; Wang, Haimin; Park, Y. D.; Gopalswamy, N.; Yang, Guo; Yashiro, S. Bibliographic Code: 2002ApJ...581..694M Abstract A comprehensive statistical study is performed to address the question of whether two classes of coronal mass ejections (CMEs) exist. A total of 3217 CME events observed by SOHO/LASCO in 1996-2000 have been analyzed. We have examined the distributions of CMEs according to speed and acceleration, respectively, and investigated the correlation between speed and acceleration of CMEs. This statistical analysis is conducted for two subsets containing those CMEs that show a temporal and spatial association either with GOES X-ray solar flares or with eruptive filaments. We have found that CMEs associated with flares have a higher median speed than those associated with eruptive filaments and that the median speed of CMEs associated with strong flares is higher than that of weak-flare-associated CMEs. The distribution of CME acceleration shows a conspicuous peak near zero, not only for the whole data set, but also for the two subsets associated either with solar flares or with eruptive filaments. However, we have confirmed that the CMEs associated with major flares tend to be more decelerated than the CMEs related to eruptive filaments. The fraction of flare-associated CMEs has a tendency to increase with the CME speed, whereas the fraction of eruptive-filament-associated CMEs tends to decrease with the CME speed. This result supports the concept of two CME classes. We have found a possibility of two components in the CME speed distribution for both the CME data associated with flares larger than M1 class and the CME data related with limb flares. Our results suggest that the apparent single-peak distribution of CME speed can be attributed to the projection effect and possibly to abundance of small flares too. We also note that there is a possible correlation between the speed of CMEs and the time-integrated X-ray flux of the CME-associated limb flares. @-------------------------------------------------------------------- Title: The International Heliophysical Year (IHY) Authors: Davila, J. M.; Harrison, R.; Poland, A.; Thompson, B.; Gopalswamy, N. Bibliographic Code: 2002AGUFMSH21A0518D Abstract In 1957 a program of international research, inspired by the International Polar Years of 1882-83 and 1932-33, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations, from pole to pole to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The fiftieth anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like it predecessors, the IHY will focus on fundamental global questions of Earth science. @-------------------------------------------------------------------- Title: Solar, Interplanetary, and Geospace Disturbances Associated with the April 2002 Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; St. Cyr, O.; Lawrence, G.; Kaiser, M. L.; Gurman, J. B.; Howard, R. A. Bibliographic Code: 2002AGUFMSA12A..02G Abstract The Solar and Heliospheric Observatory (SOHO) detected a large number of coronal mass ejections (CMEs) during the April 14-24, 2002 period. We describe the properties of these CMEs and contrast them with those of the general population of CMEs. We explore the connection of these CMEs to the interplanetary shocks and the solar energetic particles events using Wind and GOES data, respectively. We assess the extent of preconditioning of the corona by repeated flaring and mass ejections from the active regions involved. Based on the arrival times of the interplanetary CMEs and shocks, we discuss the evolution of these disturbances as they propagated between the Sun and Earth. We compare the extended nature of the main phase of the complex geomagnetic storm to other other similar extended storm periods @-------------------------------------------------------------------- Title: MHD modelling of CME and CME interactions in a bi-modal solar wind: a preliminary analysis of the 20 January 2001 two CMEs interaction event Authors: Wu, S. T.; Wang, A. H.; Gopalswamy, N. Bibliographic Code: 2002ESASP.505..227W Abstract Observations from SOHO and WIND reveal that coronal mass ejections (CMEs) cannibalize and deflect one another. CMEs also are accelerated and decelerated due to their interactions with the solar wind. These CME interactions with CME and with the solar wind result in producing significant differences in solar wind signatures as compared to isolated CME events. To understand these dynamical evolutionary processes, we have constructed a magnetohydrodynamic (MHD) simulation model based on a flux-rope and streamer model including bi-modal solar wind to investigate the physical processes of CME interactions. Specifically, the January 20, 2001 CME-CME interaction event recorded by SOHO/LASCO/C2/C3 are used to guide this simulation study. The results showed that CME cannibalism is caused by magnetic reconnection. The CME's acceleration and deceleration are caused by solar wind and the CME's deflection of one another. @-------------------------------------------------------------------- Title: Measurements of Three-dimensional Coronal Magnetic Fields from Coordinated Extreme-Ultraviolet and Radio Observations of a Solar Active Region Sunspot Authors: Brosius, Jeffrey W.; Landi, Enrico; Cook, John W.; Newmark, Jeffrey S.; Gopalswamy, N.; Lara, Alejandro Bibliographic Code: 2002ApJ...574..453B Abstract We observed NOAA Active Region 8108 around 1940 UT on 1997 November 18 with the Very Large Array and with three instruments aboard the NASA/ESA Solar and Heliospheric Observatory satellite, including the Coronal Diagnostic Spectrometer, the EUV Imaging Telescope, and the Michelson Doppler Imager. We used the right-hand and left-hand circularly polarized components of the radio observing frequencies, along with the coordinated EUV observations, to derive the three-dimensional coronal magnetic field above the region's sunspot and its immediate surroundings. This was done by placing the largest possible harmonic (which corresponds to the smallest possible magnetic field strength) for each component of each radio frequency into appropriate atmospheric temperature intervals such that the calculated radio brightness temperatures at each spatial location match the corresponding observed values. The temperature dependence of the derived coronal magnetic field, B(x,y,T), is insensitive to uncertainties on the observed parameters and yields field strengths in excess of 580 G at 2×10⁶ K and in excess of 1500 G at 1×10⁶ K. The height dependence of the derived coronal magnetic field, B(x,y,h), varies significantly with our choice of magnetic scale height L_B. Based on L_B=3.8×10⁹ cm derived from the relative displacements of the observed radio centroids, we find magnetic field strengths in excess of 1500 G at heights of 15,000 km and as great as 1000 G at 25,000 km. By observing a given target region on several successive days, we would obtain observations at a variety of projection angles, thus enabling a better determination of L_B and, ultimately, B(x,y,h). We compare coronal magnetic fields derived from our method with those derived from a potential extrapolation and find that the magnitudes of the potential field strengths are factors of 2 or more smaller than those derived from our method. This indicates that the sunspot field is not potential and that currents must be present in the corona. Alfvén speeds between 25,000 and 57,000 km s^-1 are derived for the 1×10⁶ K plasma at the centroids of the radio observing frequencies. Filling factors between 0.003 and 0.1 are derived for the 1×10⁶ K plasma at the centroids of the radio observing frequencies. @-------------------------------------------------------------------- Title: A new possibility to estimate the width, source location and velocity of halo CMEs Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2002ESASP.508..453M Abstract It is well known that the coronagraphic observations of halo CMEs are subject to projection effects. Viewing in the plane of the sky does not allow us to determine the crucial parameters defining geoeffectivness of CMEs, such as the velocity, width or source location. We assume that halo CMEs at the beginning phase of propagation have constant velocities, are symmetric and propagate with constant angular widths. Using these approximations and determining projected velocities and difference between times when CME appears on the opposite sides of the occultation disk we are able to get necessary parameters. We present consideration for the whole halo CMEs from SOHO/LASCO catalog until the end of 2000. @-------------------------------------------------------------------- Title: Estimation of projection effect of CMEs from the onset time of shock-associated type III radio burst Authors: Michalek, G.; Gopalswamy, N.; Reiner, M.; Yashiro, S.; Kaiser, M. L.; Howard, R. A. Bibliographic Code: 2002ESASP.508..449M Abstract We present a new possibility to estimate the projection effects on CME measurements. We assume that (1) high energy electrons are produced at the shock front ahead of the CME, and (2) the radio burst starts when the shock reaches open field lines (~3 R_solar). In other words, the onset time of the radio burst corresponds to the time when the CME leading edge reaches 3 R_solar. It is well known that coronagraphic observations of halo CMEs are subject to projection effects. Fortunately, the Wind/WAVES observations of type III radio bursts associated with shock waves are free from projection effects. The difference between the onset times of CMEs and radio bursts should be strongly correlated with the position of CMEs on the Sun. We found this correlation and showed that it strongly depends on a period of solar activity and source location on the Sun. Particular linear fits to the considered scattered plots can be used to further determination of source location and projection of CMEs on the plane of sky. @-------------------------------------------------------------------- Title: Interacting Coronal Mass Ejections and Solar Energetic Particles Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.; Howard, R. A.; Reames, D. V.; Leske, R.; von Rosenvinge, T. Bibliographic Code: 2002ApJ...572L.103G Abstract We studied the association between solar energetic particle (SEP) events and coronal mass ejections (CMEs) and found that CME interaction is an important aspect of SEP production. Each SEP event was associated with a primary CME that is faster and wider than average CMEs and originated from west of E45°. For most of the SEP events, the primary CME overtakes one or more slower CMEs within a heliocentric distance of ~20 R_solar. In an inverse study, we found that for all the fast (speed greater than 900 km s^-1) and wide (width greater than 60°) western hemispheric frontside CMEs during the study period, the SEP-associated CMEs were ~4 times more likely to be preceded by CME interaction than the SEP-poor CMEs; i.e., CME interaction is a good discriminator between SEP-poor and SEP-associated CMEs. We infer that the efficiency of the CME-driven shocks is enhanced as they propagate through the preceding CMEs and that they accelerate SEPs from the material of the preceding CMEs rather than from the quiet solar wind. We also found a high degree of association between major SEP events and interplanetary type II radio bursts, suggesting that proton accelerators are also good electron accelerators. @-------------------------------------------------------------------- Title: Motion of an Eruptive Prominence in the Solar Corona Authors: Filippov, B. P.; Gopalswamy, N.; Lozhechkin, A. V. Bibliographic Code: 2002ARep...46..417F Abstract A model for the nonradial motion of an eruptive prominence in the solar corona is proposed. Such motions, which can sometimes be inaccessible to observation, result in an apparent break in the causal link between eruptive prominences and coronal mass ejections. The global magnetic field of the Sun governs coronal plasma motions. The complex structure of this field can form prominence trajectories that differ considerably from a simple vertical rise (i.e., radial motion). A solar filament is modeled as a current-carrying ring or twisted toroidal magnetic rope in equilibrium with the coronal magnetic field. The global field is described using two spherical harmonics. A catastrophic violation of the filament equilibrium followed by its rapid acceleration---eruption---is possible in this nonlinear system. The numerical solution of the equations of motion corresponds well to the eruption pattern observed on December 14, 1997. @-------------------------------------------------------------------- Title: Influence of CME Interaction on Solar Proton Events During Cycle 23 Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.; Howard, R. A.; Reames, D. V.; Leske, R. A.; Von Rosenvinge, T. Bibliographic Code: 2002AGUSMSH41A..06G Abstract We studied the association between solar proton events and white-light coronal mass ejections (CMEs) that occurred during the solar cycle 23 until November 2001. Each of the SEP events was associated with a large-scale primary CME, that were faster and wider than average CMEs. For most of the proton events, the primary CME overtakes one or more slower CMEs. In order to confirm this result, we examined the association and CME interaction and energetic proton events for all the fast (speed > 900 km~s^-1) and wide (width > 60 deg) western hemispheric and halo CMEs during the study period. CMEs with energetic protons are 3 times more likely to be preceded by CME interaction than those without. We conclude that CME interaction is an important aspect of SEP acceleration. We infer that CME-driven shocks accelerate SEPs from the material of the preceding CMEs rather than from the quiet solar wind. @-------------------------------------------------------------------- Title: Properties of coronal mass ejections observed by SOHO Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; St. Cyr, O. C.; Plunkett, S. P.; Howard, R. A. Bibliographic Code: 2002AGUSMSH32A..03Y Abstract We report the characteristics of more than 4000 coronal mass ejections (CMEs) observed by the SOHO LASCO Coronagraph from January 1996 through December 2001. We have measured the speed, size, location, and acceleration of each CME, and examined the annual variation of their distributions. All of CME measurements are shown in the online catalog (http://cdaw.gsfc.nasa.gov/). Using this CME catalog, we found that (1) almost of CMEs occurred around equator during the solar minimum, while CME appeared at all latitudes during the solar maximum. (2) the average speed increases toward solar maximum from 306 km/s to 500 km/s, and slightly decreases to 482 km/s in 2001. (3) The width distribution become wider toward solar maximum. These results are consistent with those of Solwind and Skylab. @-------------------------------------------------------------------- Title: Evidence from Coronal Observations of Magnetic Field Structure in CMEs Authors: Gopalswamy, N. Bibliographic Code: 2002AAS...200.6509G Abstract The magnetic nature of coronal mass ejections has been inferred from the fact that they originate from closed magnetic field regions on the Sun such as active regions and filament regions. Although we have no direct measurement of the magnetic fields of CMEs, we can obtain useful information on the magnetic structure of CMEs from coronal observations at various wavelengths. The CME is a multithermal structure with temperatures ranging from a few kilokelvin to several megakelvin, so we need multi-wavelength observations to get a global picture of CMEs. A wide range of ground and space based instruments routinely observe CMEs. We present several examples of CMEs observed in X-ray, white light, EUV and radio wavelengths that help us understand the magnetic structure of CMEs. @-------------------------------------------------------------------- Title: Interplanetary Radio Bursts Authors: Gopalswamy, N. Bibliographic Code: 2002AAS...200.4908G Abstract Radio bursts in the interplanetary (IP) medium are indicative of solar eruptions that expel shock-driving coronal material or energetic electron beams. Type II radio bursts originate from fast-mode MHD shocks driven by coronal mass ejections (CMEs). Type III bursts are produced by energetic electrons escaping along open magnetic field lines. Occasionally, type IV bursts are also observed in the near-Sun IP medium. Radio and Plasma Waves (WAVES) experiment on board the Wind spacecraft routinely observes these radio bursts at frequencies below 14 MHz since 1994. This new radio window in the 1-14 MHz band has helped us confirm several of the well known solar-terrestrial processes and discover new processes such as the nonthermal radio emission due to colliding CMEs. The IP type II bursts are indicative of faster and wider CMEs, which are important from a space weather point of view. There is also a high degree of association between solar energetic particles and type II radio bursts implying that the same shocks accelerate protons and electrons. I provide a summary of the recent results obtained using radio and white light data. @-------------------------------------------------------------------- Title: Prominence Eruptions and CMEs: A Statistical Study Authors: Gopalswamy, N.; Shimojo, M.; Yashiro, S.; Shibasaki, K. Bibliographic Code: 2002AAS...200.3705G Abstract Prominence eruptions are thought to be an integral part of coronal mass ejections. However, recent statistical studies obtained conflicting conclusions regarding this relationship: a nearly one-to-one correspondence to a poor association. We revisited this problem using all the eruptive prominences detected automatically from the daily images obtained by the Nobeyama Radioheliograph. The images were made with a 10 min cadence so only slower eruptions could be detected from these images. During January 1996 to December 2001, there were 226 prominence eruptions detected this way and 182 of them had white light observations from the Solar and Heliospheric Observatory (SOHO) mission. When we compared the radio and white light data, we found that 76 CMEs, while only 16 remaining 8 suggesting partial eruption. We conclude that there is good association between CMEs when the prominence eruptions have a radial component of the velocity is dominant. @-------------------------------------------------------------------- Title: Properties of coronal mass ejections and relationship with solar flares Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; Howard, R. A. Bibliographic Code: 2002AAS...200.3704Y Abstract Coronal mass ejections (CMEs) associated with flares are thought to be faster than those associated with filament eruptions. However, Hundhausen (1997) examined that the relationship between CME kinetic energy and X-ray flare peak intensity, and found that there is only a weak correlation. We have measured the speed, size, location, and acceleration of more than 4000 CMEs observed by the SOHO LASCO Coronagraph from January 1996 through December 2001, providing a good opportunity to revisit the relationship between CMEs and flares. We identified flare-CME pairs as follows: Since the field of view of the LASCO C2 coronagraph limited to heliocentric distances over 2 solar radii (Ro), we cannot obtain the CME start time accurately. So, we assume that the CMEs start from 1 Ro, and estimate the start time from their height-time trajectories. Then, we looked for CMEs that occurred within flare impulsive phase. This way, we found 239 flare-CME pairs. We found a weak correlation between the CME speed and flare X-ray peak flux (correlation coefficient = 0.52). When we isolated the limb events (based on the solar source of the CMEs), we found the correlation to be poorer (0.44). We compare our results with those of Hundhausen. @-------------------------------------------------------------------- Title: Relationship Between DH Type II Radio Bursts and Energetic Particle Events Authors: Rosas, A. M.; Gopalswamy, N.; Kaiser, M. L. Bibliographic Code: 2002AAS...200.3703R Abstract A comparison of 134 interplanetary type II bursts detected by the WIND/WAVES experiment in the 1-14 MHz range is made with the solar energetic particle (SEP) events. The study period is from 1996 to 2001, which is between minimum and slightly above maximum of the current solar cycle (23). We find that approximately 74% of the IP type II bursts are related to an energetic particle event. We are continuing to investigate the reasons why some interplanetary type II radio bursts do not have energetic particle events. A longitudinal distribution of the solar sources of these events will be used to discriminate between the SEP and non-SEP type II bursts. The study will be able to tell us whether electron accelerators are also proton accelerators. This research was supported by NASA. Travel to this meeting is partly supported by the SPD Studentship Award. @-------------------------------------------------------------------- Title: New Measurements of 3-D Sunspot Coronal Magnetic Fields From Coordinated SOHO EUV and VLA Radio Observations Authors: Brosius, J. W.; White, S. M.; Landi, E.; Cook, J. W.; Newmark, J. S.; Gopalswamy, N.; Lara, A. Bibliographic Code: 2002AAS...200.0307B Abstract Three-dimensional sunspot coronal magnetograms were derived from coordinated extreme-ultraviolet (EUV) and radio observations of NOAA regions 8108 (N21E18 on 1997 November 18) and 8539 (N20W12 on 1999 May 13). The EUV spectra and images, obtained with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO) satellite, were used to derive the differential emission measure (DEM) and the plasma electron density for each spatial pixel (along each line of sight) within both regions. These were subsequently used to calculate maps of the expected thermal bremsstrahlung brightness temperature at the Very Large Array (VLA) radio observing frequencies of 1.4, 4.9, 8.4, and 15 GHz. The thermal bremsstrahlung maps reproduce neither the structure nor the intensity of the observed maps, and indicate that thermal gyroemission must dominate the observed radio emission. The radio observations were used to constrain the magnetic scale height and the gross temperature structure of the atmosphere. These, along with the DEM, electron density, and observed radio brightness temperature maps, were used to derive the temperature distribution of the coronal magnetic field strength B(T) that reproduced simultaneously the observed right-hand and left-hand circularly polarized emission at the radio observing frequencies for each spatial pixel in the images. Magnetic field strengths corresponding to 3rd harmonic gyroemission at 4.9 GHz (580 Gauss) are found in coronal plasmas at temperatures as high as 3.2 MK, while magnetic field strengths corresponding to 3rd harmonic gyroemission at 15 GHz (1800 Gauss) are found in coronal plasmas at temperatures as high as 1.6 MK. B(T) was ultimately converted to B(h) and compared with extrapolations from photospheric magnetograms. @-------------------------------------------------------------------- Title: Interplanetary radio emission due to interaction between two coronal mass ejections Authors: Gopalswamy, Nat; Yashiro, Seiji; Kaiser, Michael L.; Howard, Russell A.; Bougeret, J.-L. Bibliographic Code: 2002GeoRL..29h.106G Abstract We report on the detection of a new class of nonthermal radio emission due to the interaction between two coronal mass ejections (CMEs). The radio emission was detected by the Radio and Plasma Wave Experiment (WAVES) on board the Wind satellite, while the CMEs were observed by the white-light coronagraphs of the Solar and Heliospheric Observatory (SOHO) mission. There was no type II radio burst (metric or interplanetary) preceding the nonthermal emission. The radio emission occurred at a distance beyond 10 R_s from the Sun, where the two CMEs came in contact. Using H-alpha and EUV images, we found that the two CMEs were ejected roughly along the same path. We argue that the nonthermal electrons responsible for the new type of radio emission were accelerated due to reconnection between the two CMEs and/or due to the formation of a new shock at the time of the collision between the two CMEs. @-------------------------------------------------------------------- Title: Influence of the aerodynamic drag on the motion of interplanetary ejecta Authors: Vrsnak, Bojan; Gopalswamy, Nat Bibliographic Code: 2002JGRA..107.1019V Abstract A simple semi-empirical model for the motion of interplanetary ejecta is proposed to advance the prediction of their arrival times at Earth. It is considered that the driving force and the gravity are much smaller than the aerodynamic drag force. The interaction with the ambient solar wind is modeled using a simple expression for the acceleration $[\dot \upsilon \]$ = -gamma(upsilo-w), where w = w(R) is the distance-dependent solar wind speed. It is assumed that the coefficient gamma decreases with the heliocentric distance as gamma = alphaR^-beta, where alpha and beta are constants. The equation of motion is integrated numerically to relate the Earth transit time and the associated in situ velocity with the velocity of coronal mass ejection. The results reproduce well the observations in the whole velocity range of interest. The model values are compared with some other models in which the interplanetary acceleration is not velocity dependent, as well as with the model where the drag acceleration is quadratic in velocity $\[\dot \upsilon \]$ = -gamma₂(upsilo - w)|upsilo - w|. @-------------------------------------------------------------------- Title: CMEs: observations of all kinds Authors: Gopalswamy, Nat Bibliographic Code: 2002ocnd.confE..13G Abstract @-------------------------------------------------------------------- Title: Space Weather Study Using Combined Coronagraphic and in Situ Observations Authors: Gopalswamy, N. Bibliographic Code: 2002swsm.conf...39G Abstract @-------------------------------------------------------------------- Title: Statistical Properties of Radio-Rich Coronal Mass Ejections Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.; Howard, R. A.; Bougeret, J.-L. Bibliographic Code: 2002stma.conf..169G Abstract @-------------------------------------------------------------------- Title: Relation Between Coronal Mass Ejections and their Interplanetary Counterparts Authors: Gopalswamy, N. Bibliographic Code: 2002stma.conf..157G Abstract @-------------------------------------------------------------------- Title: Propagation of coronal mass ejections from Sun to 1 AU Authors: Manoharan, P.; Gopalswamy, N.; Yashiro, S.; Howard, R. Bibliographic Code: 2002cosp...34E2699M Abstract We report on the study of propagation characteristics of a large number of CMEs over the entire range of Sun-Earth distance. Using white-light (LASCO) and interplanetary scintillation (IPS) observations, we investigate the radial variation of the speed of CMEs. In the case of fast CMEs (initial speed 800 kms-1 ), speed declines slowly with distance (VcmeR-a where a0.05-0.1) within about 100 Rsun. Beyond this distance, the speed declines as VcmeR-b where b0.5 - 1. The evolution of size of CMEs with distance, LcmeR, suggests a pressure balance maintained between the CME and ambient solar wind at distances greater than 50 Rsun. We also report the detection of interaction between fast and slow CMEs outside the LASCO field of view. The interaction signature is seen as an unusual enhancement in the density turbulence. @-------------------------------------------------------------------- Title: Phenomena Associated with EIT Waves Authors: Thompson, B.; Biesecker, D.; Gopalswamy, N. Bibliographic Code: 2002cosp...34E2672T Abstract We discuss phenomena associated with "EIT Wave" transients. "EIT Waves" are propagating disturbances first observed in SOHO/EIT EUV images. However, a number of studies have been conducted to determine their relationship to other observations, using data from a variety of instruments. These phenomena include coronal mass ejections, flares, EUV/SXR dimmings,chromospheric waves, Moreton waves, solar energetic particle events, energetic electron events, and radio signatures. Although the occurrence of many phenomena correlate with the appearance of EIT waves, it is difficult to infer which associations are causal. The presentation will include a discussion of the correlation statistics of these phenomena. @-------------------------------------------------------------------- Title: Properties of Narrow Coronal Mass Ejections Observed with LASCO Authors: Yashiro, S.; Gopalswamy, N.; Howard, R. Bibliographic Code: 2002cosp...34E2602Y Abstract More than 4500 coronal mass ejections (CMEs) have been observed with SOHO LASCO coronagraph from January 1996 to December 2001. We have measured properties of all these CMEs and published them in an online catalog. In this paper, we describe the properties of narrow CMEs (width < 20 deg.). We investigated 675 narrow CMEs from the catalog and found that (1) the fraction of narrow CMEs increases from 5% to 15% towards solar maximum, (2) the average speed of the narrow CMEs is higher than that of the wide ones, (3) the maximum speed of narrow CMEs (1141 km/s) is much smaller than that of the wide CMEs (2604 km/s). We also found that the wide CMEs are likely to have the well known three-part structure, but narrow ones do not. Wide CMEs can be explained as due to the expansion of flux tubes, but the narrow CMEs seem to be mass flows in vertical flux tubes (streamers). @-------------------------------------------------------------------- Title: Variability of solar eruptions during cycle 23 Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. Bibliographic Code: 2002cosp...34E1260G Abstract Nearly 5000 coronal mass ejections (CMEs) were observed by the Solar and Heliospheric Observatory from the minimum to maximum of the current solar cycle (19962001). We have measured and cataloged the properties of all these CMEs. We have studied the variation of mean and median speeds and the rate of CMEs (averaged over Carrington rotations) as a function time. We compare the CME rate with those of other energetic solar events such as interplanetary type II bursts, solar energetic particle (SEP) events and metric type II bursts. This study is useful in identifying the phases of the solar cycle which show rapid variability. CMEs associated with radio bursts and SEPs belong to a separate group characterized by high speed and large width. We discuss the solar cycle variability of this energetic group in comparison with the general population of CMEs. @-------------------------------------------------------------------- Title: Origin of coronal streamer distention Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki, K.; Howard, R. Bibliographic Code: 2002cosp...34E1257G Abstract Distention of coronal streamers is considered to be one of the pre-eruption evolution of coronal mass ejections (CMEs), although how mass is added to the streamers is poorly understood. During our study of eruptive prominences and their relation to CMEs, we observed a large number of prominences associated with significant changes in the helmet streamers overlying the prominences. We used the white light images of the corona obtained by the Solar and Heliospheric Mission's Large Angle and Spectrometric Coronagraph images and the microwave images from the Nobeyama radioheliograph in Japan. We found that the streamer distention is associated with prominence eruption with mostly horizontal motion (parallel to the solar limb) or with eruptive prominences with most of the mass falling back to the solar surface. We suggest that the physical process which activates the prominences also add mass to the streamers. @-------------------------------------------------------------------- Title: An empirical model to predict the 1-AU arrival of interplanetary shocks Authors: Gopalswamy, N.; Lara, A.; Manoharan, P.; Howard, R. Bibliographic Code: 2002cosp...34E1256G Abstract We describe an empirical model to predict the 1-AU arrival of interplanetary shocks of solar origin. This model is an extension of Gopalswamy et al.'s [2001] empirical CME arrival model based on an effective acceleration acting on the CMEs as they propagate through the interplanetary medium. We measured the properties of a large number IP shocks, their solar sources and associated CMEs. Using in situ observations from Wind and ACE, we obtained the physical conditions upstream and down stream of the shock. Combining the shock data with the known piston-shock relation, we estimate the shock arrival times. We compare the estimated and actual arrival times of shocks to determine the error in our shock-arrival estimates. Reference: Gopalswamy, N., A. Lara, S. Yashiro, M. L. Kaiser, and R. A. Howard, Predicting the 1-AU Arrival Times of Coronal Mass Ejections, J. Geophys. Res., 106, 29,207, 2001 @-------------------------------------------------------------------- Title: Colliding coronal mass ejections and particle acceleration Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M.; Reames, D.; Howard, R. Bibliographic Code: 2002cosp...34E1253G Abstract Colliding Coronal Mass Ejections (CMEs) have important implications to a number of physical processes in the near-Sun interplanetary medium: Shock propagation, particle acceleration and solar wind composition. We present statistical results on large solar energetic particle events, associated CMEs and CME interaction during solar cycle 23. We show that most of the large SEP events are preceded by CME interaction. As an inverse study, we identified all the fast and wide front side CMEs from the western hemisphere and examined the SEP association and CME interaction. We found that fast and wide CMEs interacting with preceding CMEs are more likely to be associated with SEPs. We discuss the implications of the statistical results to the understanding of particle acceleration by CME-driven shocks. @-------------------------------------------------------------------- Title: Solar eruptions and long wavelength radio bursts: The 1997 May 12 event Authors: Gopalswamy, N.; Kaiser, M. L. Bibliographic Code: 2002AdSpR..29..307G Abstract We report on the cause of the 1997 May 12 type II bursts observed by ground based and space-based radio instruments. We estimate the fast mode speed in the corona as a function of heliocentric distance to identify the regions where fast mode shocks can be driven by CMEs. We find that both the coronal and the interplanetary type II bursts can be explained by shocks driven by the same CME at two different spatial domains. The fast mode speed in the corona has a peak at a heliocentric distance of ~ 3 R_solar which does not allow the coronal shock wave to propagate beyond this distance. When the CME continues to travel beyond the fast mode peak, another shock forms in the interplanetary medium where the fast mode speed falls sufficiently. From the radio observations we can infer that the plane of the sky speed of the CME is smaller than the space speed by at least a factor of 2, consistent with the location of the eruption at N21 W08. The inferred CME speed is also consistent with previous deprojected speed estimates. @-------------------------------------------------------------------- Title: Characteristics of coronal mass ejections associated with long-wavelength type II radio bursts Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J.-L. Bibliographic Code: 2001JGR...10629219G Abstract We investigated the characteristics of coronal mass ejections (CMEs) associated with long-wavelength type II radio bursts in the near-Sun interplanetary medium. Type II radio bursts in the decameter-hectometric (DH) wavelengths indicate powerful MHD shocks leaving the inner solar corona and entering the interplanetary medium. Almost all of these bursts are associated with wider and faster than average CMEs. A large fraction of these radio-rich CMEs were found to decelerate in the coronagraph field of view, in contrast to the prevailing view that most CMEs display either constant acceleration or constant speed. We found a similar deceleration for the fast CMEs (speed>900kms^-1) in general. We suggest that the coronal drag could be responsible for the deceleration, based on the result that the deceleration has a quadratic dependence on the CME speed. About 60% of the fast CMEs were not associated with DH type II bursts, suggesting that some additional condition needs to be satisfied to be radio-rich. The average width (66°) of the ratio-poor, fast CMEs is much smaller than that (102°) of the radio-rich CMEs, suggesting that the CME width plays an important role. The special characteristics of the radio-rich CMEs suggest that the detection of DH radio bursts may provide a useful tool in identifying the population of geoeffective CMEs. @-------------------------------------------------------------------- Title: Predicting the 1-AU arrival times of coronal mass ejections Authors: Gopalswamy, Nat; Lara, Alejandro; Yashiro, Seiji; Kaiser, Mike L.; Howard, Russell A. Bibliographic Code: 2001JGR...10629207G Abstract We describe an empirical model to predict the 1-AU arrival of coronal mass ejections (CMEs). This model is based on an effective interplanetary (IP) acceleration described by Gopalswamy et al. [2000b] that the CMEs are subject to, as they propagate from the Sun to 1 AU. We have improved this model (1) by minimizing the projection effects (using data from spacecraft in quadrature) in determining the initial speed of CMEs, and (2) by allowing for the cessation of the interplanetary acceleration before 1 AU. The resulting effective IP acceleration was higher in magnitude than what was obtained from CME measurements from spacecraft along the Sun-Earth line. We evaluated the predictive capability of the CME arrival model using recent two-point measurements from the Solar and Heliospheric Observatory (SOHO), Wind, and ACE spacecraft. We found that an acceleration cessation distance of 0.76 AU is in reasonable agreement with the observations. The new prediction model reduces the average prediction error from 15.4 to 10.7 hours. The model is in good agreement with the observations for high-speed CMEs. For slow CMEs the model as well as observations show a flat arrival time of ~4.3 days. Use of quadrature observations minimized the projection effects naturally without the need to assume the width of the CMEs. However, there is no simple way of estimating the projection effects based on the surface location of the Earth-directed CMEs observed by a spacecraft (such as SOHO) located along the Sun-Earth line because it is impossible to measure the width of these CMEs. The standard assumption that the CME is a rigid cone may not be correct. In fact, the predicted arrival times have a better agreement with the observed arrival times when no projection correction is applied to the SOHO CME measurements. The results presented in this work suggest that CMEs expand and accelerate near the Sun (inside 0.7 AU) more than our model supposes; these aspects will have to be included in future models. @-------------------------------------------------------------------- Title: Limb Flares, CMEs & Metric Type II Radio Bursts: A New Statistical Study Authors: Hammer, D.; Gopalswamy, N.; Yashiro, S.; Nunes, S.; Michalek, G. Bibliographic Code: 2001AGUFMSH42A0767H Abstract Past studies of the relationship between flares, coronal mass ejections(CMEs), and metric typeII radio bursts have been accomplished without the significantly larger and more detailed CME database that is available today through SOHO/LASCO observations. This abundance of CME data allows us to more accurately study the flare-CME-typeII relationship thereby permitting better substantiated conclusions. Our study examines the relationship between solar flares and their correlated CMEs and metric typeII bursts by sampling all (approximately 900) X-ray/H-alpha limb flares occurring between January 1996 and June 2001. Flare events are collected from Solar Geophysical Data (SGD) and flare location is confirmed with SOHO EIT, Yokhoh SXT, and Nobeyama Radioheliograph movies. All correlated CMEs are confirmed in LASCO/EIT movies and their parameters are obtained from the CSPSW/NRL maintained, SOHO/LASCO CME catalog. Metric typeII burst data are also obtained from SGD and from the websites of several individual observatories (Potsdam, Hiraiso, Learmonth, Izmiran, and Nancay). We will present statistical analysis on the occurrences between all three solar phenomena and how these relationships change when flare, CME, and typeII parameters change. Additionally, we will analyze how the data relates to past results (e.g. CME Speed vs. Flare Intensity, CME Speed vs. TypeII Occurrence, TypeII Onset - Flare Start vs. Starting Frequency, etc.). We will also present relationships between CME-flare-typeII onset times in addition to solar cycle effects. @-------------------------------------------------------------------- Title: A Statistical Study for Two Classes of CMEs Authors: Moon, Y.; Choe, G.; Park, Y.; Yang, G.; Wang, H.; Goode, P.; Yashiro, S.; Gopalswamy, N. Bibliographic Code: 2001AGUFMSH12B0747M Abstract MacQueen and Fisher (1983) noted the existence of two classes of CMEs; flare-associated CMEs show the highest speeds with little acceleration, wheras eruption-associated ones exhibit large accelerations. A statistical study has been performed to examine the bimodality of CMEs using the CME catalogue based on SOHO/LASCO observations from 1996 to 2000 by Yashiro and Michalek (2001). In the catalogue, we have used the speed and acceleration data obtained from height-time plots with 2nd order fits. We present the histogram of CME speed, the histogram of CME acceleration, and their speed-acceleration diagram. We have also conducted the same analysis for two different sets of data which have both time and spatial association with GOES solar flares and filaments activities (e.g., disappearing filaments), respectively. The filament data were collected from the NGDC and Big Bear Solar Observatory. Major results from this study are as follows. (1) The speed histogram for all the CMEs has a major peaks near 300km/s but does not show any double peaks. (2) Their acceleration histogram has a strong peak near zero, even for the two data sets associated with solar flares and filaments. (3) The number of CMEs with deceleration is comparable to that of CMEs with acceleration. (4) Their acceleration distribution has a maximum near zero regardless of their speed. (5) The ratio of flare-associated ones to all the CMEs increases with CME speed, wheras the ratio of filament-associated ones decreases. Finally we compare our results with previous ones and discuss their implications on the bimodality of CMEs. @-------------------------------------------------------------------- Title: Momentum Coupling Between Coronal Mass Ejections and the Solar Wind Authors: Chen, J.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2001AGUFMSH12A0740C Abstract The interaction of coronal mass ejections (CMEs) and the ambient solar wind plays a critically important role in determining the CME acceleration near the Sun and the subsequent evolution through the interplanetary medium. In particular, the speed and the magnetic field of associated magnetic clouds at 1 AU are dependent on the momentum transfer from the CME to the solar wind (SW) during the transit. Theoretically, because of the high magnetic Reynold's number, turbulent drag has been used to model the integrated drag (retarding or accelerating depending on the velocity differential) force on CMEs exerted by the SW (Chen 1996). The drag coefficient has been previously estimated to be of order unity using a 2-D MHD simulation of flux-rope interactions with an ambient magnetizid plasma consistent with SW conditions near 1 AU (Cargill et al. 1996). Such treatments posit that the momentum coupling between a flux rope and the ambient plasma is proportional to (V-V_sw)², where V is the speed of the flux rope and V_sw is the ambient SW speed. Recently, Gopalswamy et al. (2001) found that the observationally inferred drag force is approximately quadratic in CME speed, based on 61 decelerating CME events. In this paper, we examine specific events using LASCO data and determine the drag coefficient: for each event, we measure the speed-height profile and the minor radius at the leading edge; then using a model of the coronal density and SW outflow speed, estimate the drag coefficient. Work supported by ONR and NASA. Chen, J., JGR, 101, 27499, 1996 Cargill, P. J., J. Chen, D. S. Spicer, and S. T. Zalesak, JGR, 101, 4855, 1996. Gopalswamy, N., S. Yashiro, M. L. kaiser, R. A. Howard, and J.-L. Bougeret, in press, JGR, 2001. @-------------------------------------------------------------------- Title: Interacting CMEs and Solar Energetic Particles Authors: Gopalswamy, N.; Yashiro, S.; von Rosenvinge, T. T.; Leske, R. Bibliographic Code: 2001AGUFMSH12A0735G Abstract We examined the solar sources of a set of large solar energetic particle (SEP) events with mixed (impulsive + gradual) abundance signatures. The SEP events were detected by the Solar Isotope Spectrometer (SIS) on board the Advanced Composition Explorer (ACE) spacecraft. For each of the SEP events, we identified a "primary" coronal mass ejection (CME), detected by the Solar and Heliospheric observatory (SOHO). Then we examined a set of CMEs preceding the primary CME, potentially interacting with the primary CME in the near-Sun interplanetary medium. Twenty events from a list of 27 recently compiled von Rosenvinge et al. (Proc. ICRC 2001, p. 3136) overlapped with SOHO observations. Preliminary results indicate that a large majority of the primary CMEs were preceded by slower CMEs, suggesting that CME interaction may result in abundance enhancements in the source material. Research supported by NASA and AFOSR. @-------------------------------------------------------------------- Title: Interplanetary Acceleration of Coronal Mass Ejections: Comparison between numerical simulations and observations Authors: Lara, A.; Gonzalez-Esparza, A.; Perez-Tijerina, E.; Santillan, A.; Gopalswamy, N. Bibliographic Code: 2001AGUFMSH11D..10L Abstract For a set of 50 Coronal Mass Ejections (CMEs) observed with the Large Angle and Spectrometric COrongraph (LASCO) on board of the SOlar and Heliospheric Observatory (SOHO) mission, we estimate the density and measure the sky-plane speed at 18 solar radii (R_sun). We feed these parameters to a one dimensional, single fluid, hydrodynamic model to simulate the CME propagation from 18 R_sun to one AU, and iteratively adjust the initial temperature and ambient solar wind speed using in situ measurements by the Wind mission prior to and during the ICMEs that pair with the white-light CMEs. Following the evolution of the nose of the ejecta we are able to construct an acceleration model for the simulated ICMEs. We compare and discuss the simulated acceleration profile with the observed mean acceleration in order to obtain a general ICME acceleration model. @-------------------------------------------------------------------- Title: Numerical Study on the Acceleration of Coronal Mass Ejections in the Interplanetary Medium Authors: Gonzalez-Esparza, A.; Lara, A.; Perez-Tijerina, E.; Santillan, A.; Gopalswamy, N. Bibliographic Code: 2001AGUFMSH11D..09G Abstract Recently Gopalswamy et al. [2000] studied observations of ICMEs by WIND spacecraft and correlated these observations with CMEs detected previously by SOHO coronographs. They found that the Sun-Earth mean acceleration of these events was approximately proportional to their initial speeds, and they suggest that this result could be used for space weather forecasting. In this work we perform a parametric study of several CME like disturbances propagating in two different ambient winds using a one dimensional, single fluid, hydrodynamic model, to study the kinematics of the CME fronts near the Sun to 1 AU. These 1-D simulations of interplanetary disturbances have shown to be very useful to understand the basic physical aspects of the injection and heliospheric evolution of these phenomena. In this work we explore how the CME acceleration and transit time from near the Sun to 1 AU varies depending on the CME initial conditions and the ambient solar wind. @-------------------------------------------------------------------- Title: CME Interactions Near the Sun Authors: Gopalswamy, N. Bibliographic Code: 2001AGUFMSH11D..01G Abstract The phenomenon of interaction between coronal mass ejections in the near-Sun interplanetary medium is surveyed using data from SOHO and Wind missions. Long wavelength radio data (1-14 MHz) reveal CME-CME and CME-shock interactions. CME interactions may result in change of CME trajectories or merger ("cannibalism"). Typically, slower CMEs are overtaken by faster CMEs. Occasionally, multiple interactions are observed. Solar cycle variation of the CME interaction rate will be presented based on a careful examination of all the available CME data from SOHO. Finally, consequences of the CME interaction in the interplanetary medium will be discussed briefly. Research supported by NASA, AFOSR and NSF. @-------------------------------------------------------------------- Title: Statistical analysis of coronal shock dynamics implied by radio and white-light observations Authors: Reiner, M. J.; Kaiser, M. L.; Gopalswamy, N.; Aurass, H.; Mann, G.; Vourlidas, A.; Maksimovic, M. Bibliographic Code: 2001JGR...10625279R Abstract For 19 solar eruptive events we present a statistical comparison of the shock dynamics derived from the measured frequency drift rates of metric and decametric-hectometric (D-H) type II radio bursts with the dynamics of the associated coronal mass ejection (CME). We find that the shock speed parameters derived from the D-H type II radio emissions generated in the high corona (~2-4R_solarR_solar=696,000km) are well correlated with the corresponding CME plane-of-the-sky speeds (correlation coefficient=0.71). On the other hand, we find no obvious correlation between the shock speed parameters derived from the metric type II radio bursts, generated in the middle corona (1.4-2R_solar), and the corresponding CME speeds (correlation coefficient=-0.07). In general, we also find no clear correlation between the shock speed parameters derived from the metric type II bursts and the D-H radio emissions (correlation coefficient=0.3). However, the metric type II radio bursts sometimes include a second component that is possibly related to the D-H radio emissions. These statistical comparisons of the shock dynamics, implied by the observed metric and D-H type II frequency drift rates, provide further evidence for two distinct coronal shocks. Our statistical analyses are proceeded by two specific examples that illustrate the methodology used in this study. @-------------------------------------------------------------------- Title: Near-Sun and near-Earth manifestations of solar eruptions Authors: Gopalswamy, N.; Lara, A.; Kaiser, M. L.; Bougeret, J.-L. Bibliographic Code: 2001JGR...10625261G Abstract We compare the near-Sun and near-Earth manifestations of solar eruptions that occurred during November 1994 to June 1998. We compared white-light coronal mass ejections, metric type II radio bursts, and extreme ultraviolet wave transients (near the Sun) with interplanetary (IP) signatures such as decameter-hectometric type II bursts, kilometric type II bursts, IP ejecta, and IP shocks. We did a two-way correlation study to (1) look for counterparts of metric type II bursts that occurred close to the central meridian and (2) look for solar counterparts of IP shocks and IP ejecta. We used data from Wind and Solar and Heliospheric Observatory missions along with metric radio burst data from ground-based solar observatories. Analysis shows that (1) most (93%) of the metric type II bursts did not have IP signatures, (2) most (80%) of the IP events (IP ejecta and shocks) did not have metric counterparts, and (3) a significant fraction (26%) of IP shocks were detected in situ without drivers. In all these cases the drivers (the coronal mass ejections) were ejected transverse to the Sun-Earth line, suggesting that the shocks have a much larger extent than the drivers. Shocks originating from both limbs of the Sun arrived at Earth, contradicting earlier claims that shocks from the west limb do not reach Earth. These shocks also had good type II radio burst association. We provide an explanation for the observed relation between metric, decameter-hectometric, and kilometric type II bursts based on the fast mode magnetosonic speed profile in the solar atmosphere. @-------------------------------------------------------------------- Title: Introduction to special section: Global picture of solar eruptive events Authors: Gopalswamy, Nat Bibliographic Code: 2001JGR...10625135G Abstract This introduction highlights some of the scientific results reported in this special section on solar eruptive events and provides a brief description of issues related to the new results. Most of these papers grew out of the coordinated data analysis workshop held at the Goddard Space Flight Center during April 27-30, 1999, and the subsequent International Conference on Solar Eruptive Events held at the Catholic University of America, Washington, D. C. during March 6-9, 2000. @-------------------------------------------------------------------- Title: A multi-wavelength study of solar coronal-hole regions showing radio enhancements Authors: Moran, T.; Gopalswamy, N.; Dammasch, I. E.; Wilhelm, K. Bibliographic Code: 2001A&A...378.1037M Abstract We observed 17 GHz microwave-enhanced regions in equatorial coronal holes (ECH) together with extreme-ultraviolet (EUV), far-ultraviolet (FUV) and visible emissions in a search for temperature increases which might explain the bright spots in radio wavelengths. The ultraviolet (UV) observations span a wide range of formation temperatures (8000 K to 630 000 K). Increased UV emission was observed at the approximate location of the radio enhancements, but unlike the radio brightening, the UV emission did not exceed the mean quiet sun level. However, there were two observations showing increased Halpha brightness in radio enhancements above mean quiet sun levels. No Halpha bright spots were detected in ECHs outside of radio enhancement regions. The ECH Halpha bright spots were caused by bright fibrils, bright points and a lack of dark fibrils. Since the 17 GHz and Halpha enhancements are co-spatial, have equal integrated normalized enhanced emission and brightness temperatures, the observations suggest that the radio enhancements are caused by increased fibril radio emission. In addition, increased Fe XII EUV emission was recorded at the location of some well-defined radio enhancements, which were the bases of coronal plumes. Since the radio brightness temperature is much lower than the Fe xii formation temperature, the radio and EUV enhancements are likely both related to the presence of concentrated magnetic flux, but do not arise from the same physical layer. @-------------------------------------------------------------------- Title: X-ray Ejecta, White-Light CMEs and a Coronal Shock Wave Authors: Gopalswamy, N.; Cyr, O. C. St.; Kaiser, M. L.; Yashiro, S. Bibliographic Code: 2001SoPh..203..149G Abstract We report on a coronal shock wave inferred from the metric type II burst of 13 January 1996. To identify the shock driver, we examined mass motions in the form of X-ray ejecta and white-light coronal mass ejections (CMEs). None of the ejections could be considered fast (> 400 km s^-1) events. In white light, two CMEs occurred in quick succession, with the first one associated with X-ray ejecta near the solar surface. The second CME started at an unusually large height in the corona and carried a dark void in it. The first CME decelerated and stalled while the second one accelerated, both in the coronagraph field of view. We identify the X-ray ejecta to be the driver of the coronal shock inferred from metric type II burst. The shock speed reported in the Solar Geophysical Data (1000-2000 km s^-1) seems to be extremely large compared to the speeds inferred from X-ray and white-light observations. We suggest that the MHD fast-mode speed in the inner corona could be low enough that the X-ray ejecta is supermagnetosonic and hence can drive a shock to produce the type II burst. @-------------------------------------------------------------------- Title: Non-radial motion of eruptive filaments Authors: Filippov, B. P.; Gopalswamy, N.; Lozhechkin, A. V. Bibliographic Code: 2001SoPh..203..119F Abstract We develop a simple model to explain the non-radial motion of eruptive solar filaments under solar minimum conditions. The global magnetic field is derived from the first and third components of the spherical harmonic expansion of a magnetic scalar potential. The filament is modeled as a toroidal current located above the mid-latitude polarity inversion line. We investigate the stability of the filament against changes in the filament current and attempt to explain the non-radial motion and acceleration of the eruptive filament. We also discuss the limitations of this model. @-------------------------------------------------------------------- Title: Band-splitting of coronal and interplanetary type II bursts. I. Basic properties Authors: Vrsnak, B.; Aurass, H.; Magdalenic, J.; Gopalswamy, N. Bibliographic Code: 2001A&A...377..321V Abstract Patterns analogous to the band-splitting of metric type II bursts are found in a number of type II bursts observed in the dekameter-kilometer wavelength range. A similarity of morphological and frequency-time characteristics of two emission components are indicative of a common source. Relative frequency splits span in the range Delta f/f=0.05-0.6. At radial distances between 2 and 4 R_sun only small splits around 0.1 can be found. In the interplanetary space the relative split on average increases with the radial distance, whereas the inferred shock velocity decreases. In three events extrapolations of the split components point to the base and the peak of the jump in the local plasma frequency caused by the associated shock passage at 1 AU. This is suggestive of the plasma radiation from the regions upstream and downstream of the shock. Adopting this interpretation, one finds that the drop of Delta f/f at 2-4 R_sun is congruent with the Alfvén velocity maximum expected there. The split increase and the velocity decrease at larger distances can be explained as a consequence of declining Alfvén speed in the interplanetary space. @-------------------------------------------------------------------- Title: Testing the Empirical CME Arrival Model Using Earth Directed Events Authors: Lara, A.; Gopalswamy, N.; Dasso, S.; Yashiro, S. Bibliographic Code: 2001AGUSM..SH61A05L Abstract An empirical model to predict the arrival of coronal mass ejections at 1 AU was developed recently (Gopalswamy et al. 2000), based on SOHO and Wind observations. The model was further improved by correcting for the intrinsic projection effects on CME initial speed. This correction was performed using archival data from Helios-1, Pioneer Venus Orbiter and P78-1 (Solwind) spacecraft which were in quadrature so that the projection effects were minimal. In this work we use the corrected CME arrival model to predict the travel time of a large set of Earth directed halo CMEs observed by SOHO/LASCO from January 1997 to December 2000. We search for interplanetary signatures around the predicted arrival times. In particular, one of the most commonly observed characteristics of interplanetary CMEs (ICME) is their low temperature with respect to the ambient (fast and slow) solar wind. We search for low temperature regions from in situ data obtained by Wind, ACE, and IMP8 spacecraft, as a proxy to the ICMEs. Finally, we compare the predicted CME arrival times with the detected ICME times and perform a statistical analysis of the errors in the predicted time. @-------------------------------------------------------------------- Title: Origin and Early Evolution of Coronal Mass Ejections Authors: Gopalswamy, N. Bibliographic Code: 2001AGUSM..SH61A01G Abstract Simultaneous observations at multiple wavelengths over a large field of view have dramatically improved our understanding of coronal mass ejections. Extreme ultraviolet and soft X-ray observations reveal the source regions of Earth-directed CMEs. Microwave and H-alpha observations provide information on the cool components of the CMEs. Radio observations at long decametric and hectometric wavelengths trace CME-driven shock waves that just enter into the interplanetary medium. This paper summarizes recent findings on CMEs using SOHO, Yohkoh and Wind observations and discusses how near-Sun CME observations are useful in interpreting transient events in the inner heliosphere. @-------------------------------------------------------------------- Title: An Observational Study of Solar Coronal-hole Regions Showing Radio Enhancements Authors: Moran, T. G.; Gopalswamy, N.; Dammash, I.; Wilhelm, K. Bibliographic Code: 2001AGUSM..SH41A13M Abstract We observed 17~GHz microwave-enhanced regions in equatorial coronal holes (ECH) together with extreme-ultraviolet (EUV), far-ultraviolet (FUV) and visible emissions in a search for temperature increases which might explain the bright spots in radio wavelengths. The ultraviolet (UV) observations span a wide range of formation temperatures (8000~K to 630 000~K). Increased UV emission was observed at the approximate location of the radio enhancements, but unlike the radio brightening, the UV emission did not exceed the mean quiet sun level. However, there were two observations showing increased Halpha brightness in radio enhancements above mean quiet sun levels. No Halpha bright spots were detected in ECHs outside of radio enhancement regions. The ECH Halpha bright spots were caused by bright fibrils, bright points and a lack of dark fibrils. Since the 17~GHz and Halpha enhancements are co-spatial, have equal integrated normalized enhanced emission and brightness temperatures, the observations suggest that the radio enhancements are caused by increased fibril radio emission. In addition, increased Fe xii EUV emission was recorded at the location of some well-defined radio enhancements, which were the bases of coronal plumes. Since the radio brightness temperature is much lower than the Fe xii formation temperature, the radio and EUV enhancements are likely both related to the presence of concentrated magnetic flux, but do not arise from the same physical layer. @-------------------------------------------------------------------- Title: Measurements of 3-D Sunspot Coronal Magnetic Fields From Coordinated SOHO EUV and VLA Radio Observations Authors: Brosius, J. W.; Landi, E.; Cook, J. W.; Newmark, J.; Gopalswamy, N.; Lara, A. Bibliographic Code: 2001AGUSM..SH32C02B Abstract Three-dimensional sunspot coronal magnetograms were derived from coordinated extreme-ultraviolet (EUV) and radio observations of NOAA region 8108 (N21 E18) on 1997 November 18. The EUV spectra and images, obtained with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO) satellite, were used to derive differential emission measure (DEM) distributions for each spatial pixel (i.e., along each line of sight) of the region's images. These were subsequently used to calculate maps of the expected thermal bremsstrahlung brightness temperature at the Very Large Array (VLA) radio observing frequencies of 4.9 and 8.4 GHz. The thermal bremsstrahlung maps reproduce neither the structure nor the intensity of the observed maps, and indicate that thermal gyroemission must also contribute to the observed radio emission. Under the assumptions of a monotonic increase in temperature and a monotonic decrease in magnetic field strength with height above the sunspot, we derived the temperature distribution of the coronal magnetic field strength that reproduced simultaneously the observed right-hand and left-hand circularly polarized radio emission at 4.9 and 8.4 GHz for each spatial pixel in the sunspot maps. This was done by placing harmonics of the radio observing frequencies in appropriate plasma temperature intervals, integrating along the line of sight, and iterating until a solution was obtained. Magnetic field strengths corresponding to 3rd harmonic gyroemission at 4.9 GHz (580 Gauss) are found in coronal plasmas at temperatures as high as 2.2*E⁶ K, while magnetic field strengths corresponding to 2nd harmonic gyroemission at 8.4 GHz (1500 Gauss) are found in coronal plasmas at temperatures as high as 1.1*E⁶ K. @-------------------------------------------------------------------- Title: Development of SOHO/LASCO CME Catalog and Study of CME Trajectories Authors: Yashiro, S.; Gopalswamy, N.; St. Cyr, O. C.; Lawrence, G.; Michalek, G.; Young, C. A.; Plunkett, S. P.; Howard, R. A. Bibliographic Code: 2001AGUSM..SH31C10Y Abstract We present a catalog of coronal mass ejections (CMEs) based on SOHO/LASCO observations. This catalog covers the period from 1998 October to the present time. For each of the observed CMEs, the catalog contains the following information: LASCO C2 appearance time, Central Position Angle, Angular Width, height-time plots with Linear (constant speed) and 2nd order (constant acceleration) fits and corresponding speeds, and acceleration. The catalog will be open to the public via World Wide Web after proper validation. Using a preliminary version of this data set, we investigated the CME trajectories based on linear and quadratic fits to the data points. We estimated the error in the computed trajectories as follows: Generally speaking, the error in each height measurement depends on the quality of the CME feature that is tracked. So we grouped the observations into 5 classes based on the quality of the features on a 1-5 scale: Poor, Fair, Typical, Good, and Excellent. For a CME with a clear leading edge (excellent quality), the error in the measured height is small (5% of the measured height). On the other hand, for a CME with a ragged leading edge (poor quality), the error becomes larger (20% of the measured height). Based on this scheme, we assigned errorbars to the measured heights and then performed a weighted least-squares fit to the height-time trajectories. We found that for 90% of the CMEs, the linear (constant speed) fit is preferable. For the remaining 10%, quadratic fit (constant acceleration) is better than the linear fit. @-------------------------------------------------------------------- Title: Acceleration and Deceleration of CMEs Associated with Long Wavelength Radio Bursts Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. Bibliographic Code: 2001AGUSM..SH31C07G Abstract Type II radio bursts in the Decameter-Hectometric (DH) wavelengths indicate powerful MHD shocks leaving the inner corona. Almost all of these bursts are associated with massive and faster-than-average coronal mass ejections (CMEs). A particularly interesting characteristic of these DH CMEs is that they are predominantly decelerating in the coronagraph field of view. In the past, it was thought that there are mainly constant speed and accelerating CMEs. We discuss the possible explanations for the CME deceleration in the near-Sun interplanetary medium. Research supported by NASA, NSF and Air Force Office of Scientific Research @-------------------------------------------------------------------- Title: Lasco CME Speeds and Metric Type II Radio Bursts Authors: Hammer, D.; Gopalswamy, N.; Yashiro, S. Bibliographic Code: 2001AGUSM..SH22C01H Abstract We are using images obtained with LASCO to study correlations between CME parameters and the occurrence of metric Type II radio bursts. In particular, contemporary theories, based on SMM data, suggest a strict causal relationship between CME speeds and the production of metric Type II's. We will analyze how this relationship unfolds for Type II events occurring since the beginning of the LASCO mission in 1996, and look for solar cycle effects. We will also examine the speed of metric Type II's in comparison to LASCO derived CME speeds. @-------------------------------------------------------------------- Title: Estimation of projection effect of CMEs from onset time of type III radio bursts. Authors: Michalek, G.; Gopalswamy, N.; Reiner, M.; Yashiro, S. Bibliographic Code: 2001AGUSM..SH22A05M Abstract We present a new possibility to estimate the projection effect on CME measurements. We assume that (1) high energy electrons are produced at the shock front ahead of the CME, and (2) the radio burst starts when the shock reaches open field lines ( ~ 3 R). In other words, the onset time of the radio burst corresponds to the time when the CME leading edge reaches 3 R. It is well known that white light observations of halo CMEs with the LASCO coronagraph are subject projection effects. Fortunately, the Wind/WAVES experiment observations of type III radio burst associated with shock waves are free from this problems. The difference between onset times of CMEs and radio bursts should be strongly correlated with the position of CMEs on the Sun. We try to determine this correlation and use it to estimate the real starting position of CMEs. @-------------------------------------------------------------------- Title: Radio Signatures of Coronal Mass Ejection Interaction: Coronal Mass Ejection Cannibalism? Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J.-L. Bibliographic Code: 2001ApJ...548L..91G Abstract We report the first detection at long radio wavelengths of interaction between coronal mass ejections (CMEs) in the interplanetary medium. The radio signature is in the form of intense continuum-like radio emission following an interplanetary type II burst. At the time of the radio enhancement, coronagraphic images show a fast CME overtaking a slow CME. We interpret the radio enhancement as a consequence of shock strengthening when the shock ahead of the fast CME plows through the core of the preceding slow CME. The duration of the radio enhancement is consistent with the transit time of the CME-driven shock through the core of the slow CME. As a consequence of the interaction, the core of the slow CME changed its trajectory significantly. Based on the emission characteristics of the radio enhancement, we estimate the density of the core of the slow CME to be ~4×10⁴ cm^-3. The CME interaction has important implications for space weather prediction based on halo CMEs: some of the false alarms could be accounted for by CME interactions. The observed CME interaction could also explain some of the complex ejecta at 1 AU, which have unusual composition. @-------------------------------------------------------------------- Title: Early life of coronal mass ejections Authors: Gopalswamy, N.; Thompson, B. J. Bibliographic Code: 2000JASTP..62.1457G Abstract Coronal mass ejections (CMEs) are large-scale magnetized plasma structures ejected from closed magnetic field regions of the Sun. White light coronagraphic observations from ground and space have provided extensive information on CMEs in the outer corona. However, our understanding of the solar origin and early life of CMEs is still in an elementary stage because of lack of adequate observations. Recent space missions such as Yohkoh and Solar and Heliospheric Observatory (SOHO) and ground-based radioheliographs at Nobeyama and Nancay have accumulated a wealth of information on the manifestations of CMEs near the solar surface. We review some of these observations in an attempt to relate them to what we already know about CMEs. Our discussion relies heavily on non-coronagraphic data combined with coronagraphic data. Specifically, we discuss the following aspects of CMEs: (i) coronal dimming and global disk signatures, (ii) non-radial propagation during the early phase, (iii) Photospheric magnetic field changes during CMEs, and (iv) acceleration of fast CMEs. The relative positions and evolution of coronal dimming, arcade formation, prominence eruption will be discussed using specific events. The magnitude and spatial extent of CME acceleration may be an important parameter that distinguishes fast and slow CMEs. @-------------------------------------------------------------------- Title: Soft X-Ray and Gyroresonance Emission above Sunspots Authors: Nindos, A.; Kundu, M. R.; White, S. M.; Shibasaki, K.; Gopalswamy, N. Bibliographic Code: 2000ApJS..130..485N Abstract Using Yohkoh SXT and Nobeyama 17 GHz data, we have studied the soft X-ray and microwave emission above several stable, large sunspots near central meridian passage. Our study confirms the well-known fact that soft X-ray emission is depressed above sunspots. It also shows that the distribution of their soft X-ray intensity is not uniform; usually the darkest pixels are associated with the umbra or the far edges of the leading part of the penumbra while the following part of the penumbra may contain higher intensity pixels associated with brighter loops. For the first time, we present a systematic survey of the temperatures and emission measures of the soft X-ray material above sunspots. Sunspots always contain the lowest temperatures and emission measures in the active regions. The mean umbral temperature is 1.8×10⁶ K, and the mean penumbral temperature is 2.4×10⁶ K. The mean umbral and penumbral emission measures are logEM=26.60 cm^-5 and logEM=27.00 cm^-5, respectively. The differences between the umbral and penumbral plasma temperatures are physically significant. The higher penumbral values imply that the loops associated with the penumbrae are generally hotter and denser than the loops associated with the umbrae. The highest sunspot temperatures and emission measures are still lower than the average active region parameters but higher than the quiet-Sun plasma parameters. The coronal radiative energy loss rate above the umbrae is 15% higher than the radiative loss rate of the quiet-Sun plasma but a factor of 8.3 lower than the typical active region radiative loss rate. The radio emission comes from the gyroresonance mechanism, and, as expected, it is sensitive to the magnetic field rather than the soft X-ray-emitting plasma. @-------------------------------------------------------------------- Title: Erratum: ``Change in photospheric magnetic flux during coronal mass ejections'' Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig Bibliographic Code: 2000GeoRL..27.1863L Abstract @-------------------------------------------------------------------- Title: Microwave Enhancement in Coronal Holes: Statistical Propeties Authors: Gopalswamy, N.; Shibasaki, K.; Salem, M. Bibliographic Code: 2000JApA...21..413G Abstract @-------------------------------------------------------------------- Title: Magnetic Evolution and Eruptive Events Associated to Active Region 8210 Authors: Lara, A.; Gopalswamy, N. Bibliographic Code: 2000SPD....31.1403L Abstract We present a study of one active region with high flare and CME activity. From April 27 to May 5, 1998, AR8210 was crossing the south solar hemisphere and produced many flares, and at least five CMEs were related to activity in this region, some of them were homologous events. We use magnetograms from the Michelson Doppler Imager (MDI) experiment on board of the Solar Heliospheric Observatory (SOHO) to construct the time series of the photospheric magnetic elements. We compute the line of sight magnetic flux over the entire active region, and over localized areas inside the active region in which activity was detected in EUV (198 Angstroms) maps from the Extreme ultraviolet Imaging Telescope (EIT) on board of SOHO. We found considerable differences between the positive and negative fluxes computed over the entire region, the mean negative flux per pixel was 50 to 100 % greater than the positive flux. Using microwave polarization measures from Nobeyama Radio Heliograph, we were able to confirm such differences. The magnetic flux computed over AR8210 also showed a considerable increasing phase when the flare and CME activity of the region was increasing. On the other hand, we found that in general, flares occur during a maximum phase in the magnetic flux computed over localized subregions and that the major changes on this magnetic flux seems to be related to CMEs. Finally we discuss the flare and CME production, with special emphasis in the homologous events. @-------------------------------------------------------------------- Title: An Empirical Model to Predict the Arrival of CMEs at 1 AU Authors: Gopalswamy, N.; Lara, A.; Kaiser, M. L. Bibliographic Code: 2000SPD....31.0283G Abstract We describe an empirical model to predict the arrival of coronal mass ejections (CMEs) at 1 AU based on the initial speed of CMEs obtained from coronagraphs. The only input needed in this model is the measured initial speed of CMEs. This model is based on an effective acceleration that CMEs are subject to, as they propagate from the Sun to 1 AU. We developed this model based on the two-point measurements made from SOHO and Wind spacecraft. We validate our model based on older data obtained by Helios-1, P78-1, Pioneer Venus Orbiter and Solar Maximum Mission spacecraft. We discuss the merits and limitations of this model. Research supported by the National Research Council, NSF, and NASA. @-------------------------------------------------------------------- Title: SOHO and radio observations of a CME shock wave Authors: Raymond, John C.; Thompson, Barbara J.; St. Cyr, O. C.; Gopalswamy, Nat; Kahler, S.; Kaiser, M.; Lara, A.; Ciaravella, A.; Romoli, M.; O'Neal, R. Bibliographic Code: 2000GeoRL..27.1439R Abstract A 1200 kms^-1 Coronal Mass Ejection was observed with the SOHO instruments EIT, LASCO and UVCS on June 11, 1998. Simultaneously, Type II radio bursts were observed with the WAVES experiment aboard the Wind spacecraft at 4 MHz and by ground-based instruments at metric wavelengths. The density in the shock wave implied by the higher frequency is close to that inferred from the SOHO/UVCS experiment. The drift rates of the Type II radio bursts suggest shock speeds lower than the speed derived from SOHO observations. The SOHO/UVCS spectrum shows enhanced emission in lines of O⁵⁺ and Si¹¹⁺, consistent with modest compression in an MHD shock. @-------------------------------------------------------------------- Title: Change in photospheric magnetic flux during coronal mass ejections [ Erratum: 2000GeoRL..27.1863L ] Authors: Lara, A.; Gopalswamy, N.; Deforest, C. Bibliographic Code: 2000GeoRL..27.1435L Abstract @-------------------------------------------------------------------- Title: Radio-rich Solar Eruptive Events Authors: Gopalswamy, N.; Kaiser, M. L.; Thompson, B. J.; Burlaga, L. F.; Szabo, A.; Vourlidas, A.; Lara, A.; Yashiro, S.; Bougeret, J.-L. Bibliographic Code: 2000GeoRL..27.1427G Abstract @-------------------------------------------------------------------- Title: Structure of a Large low-Latitude Coronal Hole Authors: Bromage, B. J. J.; Alexander, D.; Breen, A.; Clegg, J. R.; Del Zanna, G.; DeForest, C.; Dobrzycka, D.; Gopalswamy, N.; Thompson, B.; Browning, P. K. Bibliographic Code: 2000SoPh..193..181B Abstract Coronal holes on the Sun are the source of high-speed solar wind streams that produce magnetic disturbances at the Earth. A series of multi-wavelength, multi-instrument observations obtained during the 1996 `Whole Sun Month' campaign examined a large coronal hole in greater detail than ever before. It appeared on the Sun in August, and extended from the north pole to a large active region in the southern hemisphere. Its physical and magnetic structure and subsequent evolution are described. @-------------------------------------------------------------------- Title: Observations of the 24 September 1997 Coronal Flare Waves Authors: Thompson, B. J.; Reynolds, B.; Aurass, H.; Gopalswamy, N.; Gurman, J. B.; Hudson, H. S.; Martin, S. F.; St. Cyr, O. C. Bibliographic Code: 2000SoPh..193..161T Abstract We report coincident observations of coronal and chromospheric `flare wave' transients in association with a flare, large-scale coronal dimming, metric radio activity and a coronal mass ejection. The two separate eruptions occurring on 24 September 1997 originate in the same active region and display similar morphological features. The first wave transient was observed in EUV and Halpha data, corresponding to a wave disturbance in both the chromosphere and the solar corona, ranging from 250 to approaching 1000 km s^-1 at different times and locations along the wavefront. The sharp wavefront had a similar extent and location in both the EUV and Halpha data. The data did not show clear evidence of a driver, however. Both events display a coronal EUV dimming which is typically used as an indicator of a coronal mass ejection in the inner corona. White-light coronagraph observations indicate that the first event was accompanied by an observable coronal mass ejection while the second event did not have clear evidence of a CME. Both eruptions were accompanied by metric type II radio bursts propagating at speeds in the range of 500-750 km s^-1, and neither had accompanying interplanetary type II activity. The timing and location of the flare waves appear to indicate an origin with the flaring region, but several signatures associated with coronal mass ejections indicate that the development of the CME may occur in concert with the development of the flare wave. @-------------------------------------------------------------------- Title: Space VLBI at Low Frequencies Authors: Jones, D. L.; Allen, R.; Basart, J.; Bastian, T.; Blume, W.; Bougeret, J.-L.; Dennison, B.; Desch, M.; Dwarakanath, K.; Erickson, W.; Farrell, W.; Finley, D.; Gopalswamy, N.; Howard, R.; Kaiser, M.; Kassim, N.; Kuiper, T.; MacDowall, R.; Mahoney, M.; Perley, R.; Preston, R.; Reiner, M.; Rodriguez, P.; Stone, R.; Unwin, S.; Weiler, K.; Woan, G.; Woo, R. Bibliographic Code: 2000aprs.conf..265J Abstract At sufficiently low frequencies, no ground-based radio array will be able to produce high resolution images while looking through the ionosphere. A space-based array will be needed to explore the objects and processes which dominate the sky at the lowest radio frequencies. An imaging radio interferometer based on a large number of small, inexpensive satellites would be able to track solar radio bursts associated with coronal mass ejections out to the distance of Earth, determine the frequency and duration of early epochs of nonthermal activity in galaxies, and provide unique information about the interstellar medium. This would be a ``space-space" VLBI mission, as only baselines between satellites would be used. Angular resolution would be limited only by interstellar and interplanetary scattering. @-------------------------------------------------------------------- Title: Radial Evolution and Turbulence Characteristics of a Coronal Mass Ejection Authors: Manoharan, P. K.; Kojima, M.; Gopalswamy, N.; Kondo, T.; Smith, Z. Bibliographic Code: 2000ApJ...530.1061M Abstract We investigate a coronal mass ejection (CME) associated with an X3.9 solar flare that occurred on 1992 June 25. This long-duration event showed a system of large postflare loops at the activity site throughout the period of the enhanced X-ray emission. The drift rate of the metric type IV radio burst observed near the X-ray maximum suggests the speed of the ejecta to be ~350 km s^-1 at heights <=2 solar radii. The solar proton intensities, in the energy range 1-100 MeV observed in the interplanetary medium, show gradual-decay profiles lasting for more than two days and suggest CME-driven acceleration near the Sun. The inference on the spatial and kinematical characteristics of the propagating CME in the inner heliosphere (0.2-1 AU) is primarily based on the interplanetary scintillation observations at 327 MHz, obtained from the Ooty Radio Telescope and the Solar-Terrestrial Environment Laboratory. The scintillation data show the deceleration of propagating disturbance speed, V_CME~R^-0.8, in the interplanetary medium. The speeds obtained from the radio and scintillation measurements also suggest that the coronal shock may not be directly related to the interplanetary shock. The size of the CME in the interplanetary medium seems to follow a simple scaling with distance from the Sun, indicating the pressure balance maintained between the ejecta and the ambient solar wind. The density turbulence spectrum of the plasma carried by the propagating disturbance seems to be flat, Phi_{N_e(IPD)}~kappa^-2.8, also having a small dissipative scale length, S_i(IPD)<=5 km. The spectrum is significantly different from that of high-speed flow from coronal holes and low-speed wind originating above closed-field coronal streamers. @-------------------------------------------------------------------- Title: The Catholic University of America, Institute for Astrophysics and Computational Sciences, Department of Physics, Washington, District of Columbia 20064. Report for the period Sep 1998 - Sep 1999. Authors: Gopalswamy, N. Bibliographic Code: 2000BAAS...32...32G Abstract @-------------------------------------------------------------------- Title: Shock Wave and EUV Transient During a Flare Authors: Gopalswamy, N.; Kaiser, M. L.; Sato, J.; Pick, Monique Bibliographic Code: 2000ASPC..206..351G Abstract A metric type II burst and a 'brow' type enhancement in EUV were observed during the hard X-ray flare of 1997 April 15 from a newly emerging region, AR 8032. The position of the type II burst obtained from the Nancay radioheliograph coincided with the EUV transient. The type II burst and the EUV transient were in the equatorial streamer region to the north of the flaring region. This observation suggests that the EUV transient may be the manifestation of the MHD shock responsible for the type II burst. @-------------------------------------------------------------------- Title: The Astronomical Low Frequency Array: A Proposed Explorer Mission for Radio Astronomy Authors: Jones, D.; Allen, R.; Basart, J.; Bastian, T.; Blume, W.; Bougeret, J.-L.; Dennison, B.; Desch, M.; Dwarakanath, K.; Erickson, W.; Finley, D.; Gopalswamy, N.; Howard, R.; Kaiser, M.; Kassim, N.; Kuiper, T.; MacDowall, R.; Mahoney, M.; Perley, R.; Preston, R.; Reiner, M.; Rodriguez, P.; Stone, R.; Unwin, S.; Weiler, K.; Woan, G.; Woo, R. Bibliographic Code: 2000ralw.conf..339J Abstract A radio interferometer array in space providing high dynamic range images with unprecedented angular resolution over the broad frequency range from 0.03 - 30 MHz will open new vistas in solar, terrestrial, galactic, and extragalactic astrophysics. The ALFA interferometer will image and track transient disturbances in the solar corona and interplanetary medium - a new capability which is crucial for understanding many aspects of solar-terrestrial interaction and space weather. ALFA will also produce the first sensitive, high-angular-resolution radio surveys of the entire sky at low frequencies. The radio sky will look entirely different below about 30 MHz. As a result, ALFA will provide a fundamentally new view of the universe and an extraordinarily large and varied science return. @-------------------------------------------------------------------- Title: Type II Solar Radio Bursts Authors: Gopalswamy, N. Bibliographic Code: 2000ralw.conf..123G Abstract @-------------------------------------------------------------------- Title: Interplanetary acceleration of coronal mass ejections Authors: Gopalswamy, N.; Lara, A.; Lepping, R. P.; Kaiser, M. L.; Berdichevsky, D.; St. Cyr, O. C. Bibliographic Code: 2000GeoRL..27..145G Abstract Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an ``effective'' acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed naturally divides CMEs into fast and slow ones. Based on the relation between the acceleration and initial speed, we derive an empirical model to predict the arrival of CMEs at 1 AU. @-------------------------------------------------------------------- Title: Time Evolution of Microwave and Hard X-ray Spectral Indexes Authors: Lara, A.; Gopalswamy, N. Bibliographic Code: 2000ASPC..206..355L Abstract @-------------------------------------------------------------------- Title: The ALFA Medium Explorer Mission Authors: Jones, D. L.; Allen, R. J.; Basart, J. P.; Bastian, T.; Blume, W. H.; Bougeret, J.-L.; Dennison, B. K.; Desch, M. D.; Dwarakanath, K. S.; Erickson, W. C.; Farrell, W.; Finley, D. G.; Gopalswamy, N.; Howard, R. E.; Kaiser, M. L.; Kassim, N. E.; Kuiper, T. B. H.; MacDowall, R. J.; Mahoney, M. J.; Perley, R. A.; Preston, R. A.; Reiner, M. J.; Rodriguez, P.; Stone, R. G.; Unwin, S. C.; Weiler, K. W.; Woan, G.; Woo, R. Bibliographic Code: 2000AdSpR..26..743J Abstract The frequency range below a few tens of MHz is unexplored with high angular resolution due to the opacity of Earth's ionosphere. An interferometer array in space providing arcminute angular resolution images at frequencies of a few MHz would allow a wide range of problems in solar, planetary, galactic, and extragalactic astronomy to be attacked. These include the evolution of solar radio emissions associated with shocks driven by coronal mass ejections and searches for coherent radio emission from supernova remnants and relativistic jets. In addition, it is likely that unexpected objects or emission processes will be discovered by such an instrument, as has always happened when high resolution astronomical observations first become possible in a new region of the electromagnetic spectrum. The Astronomical Low Frequency Array (ALFA) mission will consist of 16 identical small satellites forming an aperture synthesis array. The satellites will cover the surface of a spherical region. ~100 km in diameter, thus providing good aperture plane coverage in all directions simultaneously. The array will operate in two modes: 1) ``snapshot'' imaging of strong, rapidly changing sources such as solar radio bursts and 2) long-term aperture synthesis observations for maximum sensitivity, high dynamic range imaging. In both cases a large number of array elements is needed @-------------------------------------------------------------------- Title: Structure and Dynamics of the Corona Surrounding an Eruptive Prominence Authors: Gopalswamy, N.; Hanaoka, Y.; Hudson, H. S. Bibliographic Code: 2000AdSpR..25.1851G Abstract We report on the 1997 December 14 prominence eruption event that was accompanied by eruptive signatures in X-rays, EUV and white light: coronal dimming, X-ray arcade formation, X-ray brightenings, EUV eruption, and a white light CME. The data used were obtained by the Nobeyama Radioheliograph, Yohkoh Soft X-ray Telescope (SXT) and SOHO/LASCO and EIT. We identified various substructures of the eruption and their inter-relationships. We found that the pre-disruption swelling of the equatorial streamer was caused by the outward displacement of the coronal material around the prominence location. The dynamical behaviors of the CME and the accompanying eruptive prominence seem to be very different @-------------------------------------------------------------------- Title: The Astronomical Low Frequency Array (ALFA): Imaging from Space Authors: Gopalswamy, N.; Kaiser, M. L.; Jones, D. L.; The Alfa Team Bibliographic Code: 1999spro.proc..447G Abstract The ALFA mission is a proposed astronomical observatory in space to make high resolution radio images at frequencies below the ionospheric cutoff (~ 20 MHz). This multi-satellite interferometric array will image solar as well as non-solar phenomena in the frequency range 0.03 - 30 MHz. In this paper, we provide an overview of the ALFA mission, with particular emphasis on solar studies to be undertaken. @-------------------------------------------------------------------- Title: Multi-wavelength Signatures of Coronal Mass Ejection Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Thompson, B. J.; Plunkett, S. Bibliographic Code: 1999spro.proc..207G Abstract We report on the near-surface and outer coronal manifestations of the 1998 January 25 coronal mass ejection (CME) using white light, EUV, X-ray and hectometric radio data which reveal the three dimensional structure and long term evolution of the CME. We find that (i) the substructures of the CME (prominence core, cavity, frontal structure and the arcade formation) are clearly observed in X-ray and EUV wavelengths. (ii) The filament heats up early on and is observed as a backbone in X-rays. (iii) The filament also expands considerably as it erupts. (iv) The CME is observed through direct leading edge signature as well as through dimming process in X-rays and in EUV. @-------------------------------------------------------------------- Title: X-ray and Microwave Signatures of Coronal Mass Ejections Authors: Gopalswamy, N. Bibliographic Code: 1999spro.proc..141G Abstract X-ray and microwave imaging of structures associated with coronal mass ejections (CMEs) have provided a wealth of new information towards a better understanding of solar eruptions. I review the recent research based on microwave imaging from the Nobeyama Radioheliograph and X-ray imaging from the Yohkoh Soft X-ray Telescope. I shall discuss the advances made towards understanding the near surface manifestations of CMEs best observed in X-rays and microwave