Within this project, processes in the atmosphere for varying atmospheric conditions will be investigated with different observational methods, where the main intention is to observe the three-dimensional / four-dimensional cloud field structure and related variabilities with remotely sensed and ground based observations. Thus, a synergy between vertical profiles (from ground measurements) and horizontal structures (from remotely sensed data) must be carried out to characterize and quantify the three-dimensional cloud and humidity field.
The study will use current (NOAA-AVHRR, ERS-1/2 ATSR and Meteosat) and future (Envisat AATSR and Meteosat Second Generation) satellite data to infer cloud cover, horizontal cloud structure, cloud top height, cloud optical depth and cloud microphysical properties. To derive the three-dimensional cloud field, vertical atmospheric profiles (from radar and lidar observations) will be additionally considered. Based on these observations, a synergy-technique will be developed using statistical techniques, where either modeled cloud structures or the observations will be taken into account. Applying a three-dimensional radiative transfer scheme (SHDOM) the outgoing radiances will be computed and compared with the measured radiances at satellite level to quantify the uncertainties in the determination of the three-dimensional cloud field. Additionally surface observations and airborne measurements will be used to validate the inferred optical cloud properties.
Applying the synergy-technique, for a few intensive periods various data sets will be analysed to infer the temporal variability of the cloud and humidity field. And using these results the flux densities at various levels and therefore the flux divergences for related layers will be computed and compared with modelled flux densities and divergencies. These results will further be used to study the influence of clouds on the radiation field and on the energy fluxes at surface for different temporal and spatial scales.
Department of Meteorology
Institute of Hydrology and Meteorology
Dresden University of Technology
01737 Tharandt, Germany