Estimation of precipitation based on POLRAD radar network and NIMROD system in Poland

The approach based on combination of raingauge measurements and radar rainfall estimates is investigated in order to improve spatially distributed precipitation input to flood protection system in Poland. Radar data are provided by the POLRAD – Polish Weather Radar Network consisting of 8 Doppler C-Band radars.

At first step the radar data is subject to processing with the NIMROD – British Met Office system, which performs both precipitation corrections and nowcasting. The data is corrected according to ground clutter and anaprop removal scheme, VPR and mean field bias corrections.

Next hourly precipitation accumulations are produced taking account of spatial and temporal interpolation. The method is based on dwelling-time for each precipitation pixel. The final stage of the work presented herein is combination of processed radar and raingauge information. The method employed is a conditional merging proposed by Sinclair and Pegram with using Kriging technique for spatial interpolation of point data.

The obtained estimates of precipitation field are tested as an input to System of Hydrology in Poland. In the frame of the system specific kinds of models are applied according to catchment size (from hundreds to thousands square kilometres), type (mountainous, lowland), etc.