Future master projects (proposals for the year 2015)

1. Relation between cloud cover and surface parameters, such as relative humidity

The aim of this research project is to derive, from observations, a relation between relative humidity at the ground and total-, low-, middle- and high-cloud cover fraction, using data obtained with the Cloud Cover NubiScope at Cabauw in 2011 (https://guest:guest@data.knmi.nl/portal/KNMI-DataCentre.html#). The observations will compared with the ERA-Iterim re-analysis. It might also be possible to study this relation with a large-eddy model.

2. The Brewer-Dobson circulation in idealized baroclinic life-cycles

The Brewer-Dobson circulation transports mass from the equator to the pole in the upper troposphere and stratosphere. It is not known how much of the return mass-flow towards the equator occurs near the earth's surface in association with cold air outbreaks in connection with baroclinic waves. This research project aims to investigate this question using the reanalysis and by determining the parameter-dependence of the equatorward flow of mass in baroclinic life cycles, using an idealized primitive equation model.

3. The diabatic circulation and the northern annular mode (NAM)

This project investigates the role of cross-isentropic flow and wave-induced mass fluxes in determining NAM-variations using the ERA-Interim reanalysis.

4. Mixing of potential vorticity in the upper troposphere and lower stratosphere in relation to the strength of the subtropical jet and the sign of the northern annular mode.

Isentropic mixing of potential vorticity in the Middleworld (e.g. at 350 K) across the zonal average tropopause (i.e. the zonal average position of the 2 PVU PV-isoline) is governed by Rossby waves. The question which is adressed in this research project is the following. Are these Rossby waves excited mainly in the extra tropics, or are the tropics the principal source of these waves?