A Simulation-based Study on Effects of Multiple-scattering and Attenuation in GPM DPR Measurement

A preliminary examination of the effects of multiple-scattering and attenuation is made for a dual-frequency precipitation radar (DPR) onboard the Global Precipitation Measurement (GPM) core satellite. The DPR is operated using Ku-band and Ka-band electromagnetic waves, and space-borne radar observations with Ka-band wavelength is the first attempt for the accurate estimation of precipitation. Ka-band received signals, however, may suffer from multiple-scattering due to a large footprint. Both of received signals can be attenuated by precipitation particles within a radar beam.

This study examines those effects using our radar simulator which has been developed based on the radiative transfer theory, especially the T-matrix method. Simulated results for several rain regimes and the DPR configuration indicate that the effect of multiple-scattering is prominent in Ka-band received signals even when the rain rate is relatively weak or when attenuation effect is a little bit large. The degree of multiple-scattering could be estimated by the ratio of the total received signal (Ku-band) to the total received signal (Ka-band). The comparison with a ground-based polarimetric radar data will be also presented for the validation and the correction of DPR data.