Preliminary Study with a Numerical Radar Simulator for Evaluating the Potential of GPM DPR Spaceborne Radar for Precipitation Measurement

   The dual-frequency precipitation radar (DPR) onboard the Global Precipitation Measurement (GPM) core satellite operated at frequencies of Ku- and Ka-bands has the potential to measure more accurate rain rate than the precipitation radar operated at single Ku-band frequency onboard the Tropical Rain Measuring Mission (TRMM) satellite. Although the additional use of Ku-band radio wave for DPR is expected to be useful for discrimination between rain and snow with accuracy, the algorithm that uses only dual-frequency radar data has not been developed for precipitation type discrimination. The current DPR algorithm refers a temperature profile assumed, and a previous method proposed using the differential frequency ratio (DFR) data from dual-frequency radar does not account for attenuation effects of radio waves. In this communication, the potential of DPR for precipitation measurement is evaluated using our numerical radar simulator that describes theoretically scattering properties based on a T-matrix method. Precipitation size distribution (PSD) for radar simulator is simulated by a bin-type microphysical (MP) model, so that we can consider more realistic distribution of precipitation. The introduction of such a MP model is important for the evaluation especially for mixed phase cases. The accuracy of precipitation amount estimated is evaluated in this framework. The advantage of DPR configuration will be addressed by comparison with TRMM case. The performance of our DFR-based method of precipitation type discrimination accounting attenuation effects is also evaluated. In this evaluation, effects of rainfall/snowfall rate, path-integrated reflectivity, PSD, and mixing condition will be discussed through examining with various vertical precipitation profiles.