Abstract : N.1
Real time precipitation downscaling

Reinhold Steinacker, Stefan Schneider, Manfred Dorninger
University of Vienna, Institute of Meteorology and Geophysics

High resolution precipitation analysis in real time is a highly important issue for flood or avalanche forecasting. Although high resolution models are increasingly able to forecast useful precipitation amounts, the local distribution and timing still lacks of the necessary precision. Therefore it is important to monitor precipitation with the highest possible accuracy in real time to validate model precipitation and to feed hydrological models. Radar is commonly used to downscale the precipitation field. Over complex terrain, however, the radar information is less accurate to estimate the surface precipitation due to Radar shading and low level precipitation modification. A method is proposed where the downscaling of precipitation by radar is done in an optimal way. The weight of the radar pattern in the analysis is taken variable in space and time and derived directly from station observation data. The same method may be used for real time model validation and hence as nowcasting tool. Case studies are being shown to demonstrate the potential of the method.