Das Projekt "Space-time variability of the microstructure of precipitation at the radar-subgrid scale" wird vom Umweltbundesamt gefördert und von Ecole Polytechnique Federale de Lausanne (EPF), Institut d'Amenagement des Terres et des Eaux (IATE) durchgeführt. Ground-based and spaceborne weather radars provide a wealth of remotely sensed precipitation measurements. A key issue for the quantitative use of these data in various applications is the space-time variability of the microstructure of precipitation, described by the drop size distribution (DSD hereafter). Although the variability of rainfall intensity at scales smaller than the radar resolution (radar-subgrid scales hereafter) has been studied extensively, there is no large-enough data set on the spatial variability of the DSD at radar-subgrid scales to perform robust spatial analyses. The aim of this proposal is to set up an experiment addressing this lack by deploying a network of 14 disdrometers covering the typical radar pixel (i.e. about 1x1ca.km2 for ground-based radars, and about 5x5 km2 for spaceborne radars). From the data collected, the space-time variability of the DSD will be quantified and characterized. Its influence on the accuracy of the estimation of precipitation using radar will be investigated. In particular, a stochastic simulator of space-time fields of DSD will be developed to provide a useful tool for the evaluation of the different precipitation remote sensing techniques and the associated retrieval algorithms.