I am very much interested in studying the dynamics of boundary layer clouds like stratocumulus and shallow cumulus clouds. To this end our group is using a Large-Eddy model to simulate turbulence in these clouds. We typically use observations as a basis for model initialization, while, in turn, observations of turbulence can directly be used to compare with the modeling results. If the model is capable to realistically reproduce the observations, its major advantageis that sensitivity studies can be performed. For example, one can study how small temperature or humidity fluctations affect the turbulence structure, from which we may learn how these cloud systems behave. Most of our modeling exercitions are performed at the Dutch Supercomputer "Huygens" installed in Amsterdam.

Because weather forecast and climate models use a rather coarse grid resolution, the turbulent eddies in the boundary layer are not resolved by these models. Therefore their bulk effect on the vertical transport of heat, moisture and momentum must be calculated by means of parameterizations. This is were the observations and Large-Eddy Simulation model results and the observations turn out to be vital.

Our group has a strong collaboration with our colleagues from the Dutch Royal Meteorological Office (KNMI). Various students have done an internship or a Master's research project at the KNMI, and observations collected at the 200 m tall Cabauw meteorological tower operated by the KNMI have been served as research data sets for our students.

We are currently involved in a European Union funded research programme, EUCLIPSE. The main question is to study the cloud feedback on a future climate change and to reduce the uncertainty in the representation of cloud processes and feedbacks in the new generation of cloud models. A nice movie about the project has been made for EURONEWS.