Remote Sensing of Precipitation Using Reflected GNSS Signals: Response Analysis of Polarimetric Observations

For the first time, rain effects on polarimetric observations of global navigation satellite system reflectometry (GNSS-R) are investigated. The physical feasibility tracking modifications in surface roughness by splash and salinity accumulation freshwater is theoretically discussed. An empirical analysis carried out using measurements a coastal GNSS-R station with two side-looking antennas right- left-handed circular polarizations (RHCP LHCP). Discernible drops RHCP LHCP powers observed during over calm sea. power drop becomes larger at higher elevation angles. average $\approx ~5$ dB an angle 45°. amplitude correlation sum shows dampening, responding to rate systematically. show sensitivity rainfall compared observations. retrieved standard deviation heights steady increase rate. derived decrease rains than 10 mm/h. This study confirms potential under environmental conditions ground-based station, e.g., mostly lower 30 psu, sea, being starting point for future investigations.