Progress Toward Validation of Quikscat Ultra-High-Resolution Rain Rates using TRMM PR

Although originally designed solely for wind retrieval, the QuikSCAT scatterometer has also proved to be a useful tool for rain retrieval. Resolution enhancement algorithms designed for QuikSCAT allow for ultra-high-resolution (UHR) (2.5 km) simultaneous wind and rain (SWR) retrieval. To enable SWR retrieval, we adjust the geophysical model function (GMF) to account for rain effects such as attenuation or increased backscatter due to increased surface roughness. Comparisons of a co-located data set show that QuikSCAT UHR SWR rain rates are comparable to those from Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) but have higher variance. The noise level of the QuikSCAT rain estimates can be reduced by forming the reduced resolution rain rate estimates. As expected, rain estimates are significantly worse in regions where wind dominates the backscatter.