Clouds play a key role in hydrological cycle and radiative transfer. However, they usually occur on a sub-grid scale in respect of most general circulation models, thus parameterizations based on assumptions and observations are needed. 

Aim of this project is the investigation of macro-physical cloud parameterizations, such as cloud fraction and cloud overlap: long-term ground-based observations will be used to assess how reliable  these parameterizations are and derived cloud overlap metrics will be  used to validate LES simulations.

Besides, this PhD aims also at implementing and assessing new observational techniques based on a synergy of ground-based scanning cloud radar and microwave radiometer, which may eventually lead to improved parameterizations. Cloud radar scans can provide information on the 3D-structure of clouds, on liquid water content, on the phase of cloud droplets and even on turbulence within the cloud itself; microwave radiometer can add further information on liquid water path.  A short secondment to METEK, the cloud radar manufacturing company, will help optimizing scanning patterns and operational parameters.

Long-term observations carried out at the Jülich ObservatorY for Cloud Evolution (JOYCE) facilities will be used to derive  3D fields of cloud occurrence with a high
spatial resolution (100m) for domains of about 20km, which will be used as input in a 3D radiative transfer model currently being developed at the University of Reading, where a secondment is also scheduled.