A Sentinel-1 Synthetic Aperture Radar Image of Heavy Rainfall Process Compared with GPM DPR Data

This study utilizes nearly synchronous Sentinel-1 Synthetic Aperture Radar (SAR) data and dual-frequency precipitation radar (DPR) data from the Global Precipitation Measurement mission (GPM) to analyze the effect and sensitivity of a significant precipitation event in the Amazon region on the normalized radar cross-section (NRCS) attenuation for HH/HV. Additionally, by comparing the changes in NRCS obtained from two consecutive observations, the rainfall intensity was also estimated. The results reveal that the maximum attenuation of HH/HV NRCS caused by heavy precipitation exceeded 8 dB, and the sensitivity of HH polarization and HV polarization showed significant consistency in response to rainfall attenuation. Furthermore, the rainfall rate derived from SAR signal attenuation is highly consistent with the GPM DPR rainfall rate.