QuikSCAT Radiometer (QRad) rain rates for wind vector quality control

Abstract

The SeaWinds scatterometer onboard the QuikSCAT satellite measures the ocean normalized radar cross section to infer the surface wind vector. In addition, SeaWinds simultaneously measures the polarized microwave brightness temperature of the ocean/atmosphere, and this passive microwave measurement capability is known as the QuikSCAT Radiometer (QRad). QRad brightness temperatures are used to infer instantaneous rain rates over oceans using a statistical retrieval algorithm that has been developed using collocated QRad brightness temperatures with TRMM Microwave Imager (TMI) rain rate measurements. In this paper, QRad retrieved rain rate examples are presented and comparisons are made with independent near simultaneous rain observations including the TRMM 3B42RT data product. This near-real-time global precipitation data product combines all passive microwave with geostationary visible/infrared precipitation estimates in global 3-hour universal time windows. Results demonstrate that QRad rain measurements agree well with these independent microwave rain observations, which demonstrates the utility of using QRad rain retrievals as a "stand alone rain quality flag".