Effects of rain on CFOSAT scatterometer measurements

The Ku-band scatterometer onboard China France Oceanography Satellite (CFOSAT) observes the sea surface with two conically scanning fan beams. Compared to prior pencil beam scatterometers, this innovative observing mechanism provides more independent backscatter measurements at varying incidence and azimuth angles, as such it brings challenges for wind inversion, particularly under rainy conditions. In paper, rain effects on CFOSAT SCATterometer (CSCAT) are investigated using collocated numerical weather prediction (NWP) data Global Precipitation Measurement (GPM) microwave imager (GMI) data. Similar or C-band sensitivity of CSCAT radar substantially varies speed, polarization angle. However, due complex observation geometries, retrieved winds is than that which may lead a remarkable underestimation speed high heavy A simple simulation method used clarify relation between dependency It found low generally underestimated conditions, have larger influence inversion minimization, leading much lower speeds those ECMWF (e.g., Haiyang-2B scattometer). Under moderate conditions though, compensated effect angle found, unbiased winds, in contrast pencil-beam winds.