Simultaneous wind and rain retrieval for ERS scatterometer measurements

Using collocated ESCAT, TRMM PR, and ECMWF data, the effects of rain on the ESCAT wind-only retrieval has been evaluated. For high incidence angle measurements, the additional scattering of rain causes estimated wind speeds to appear higher than expected. It is also noted that the selected directions of the rain-corrupted wind vectors generally point along swath in heavy rain, regardless of the true wind. A simultaneous wind/rain retrieval method (SWRR) is developed using a simple wind/rain backscatter model. Validation shows that SWRR method significantly improves the wind vector estimates at high incidence angles in heavy rain cases. It also provides an estimate of the surface rain rate.