Ocean Vector Wind Measurements from GPM to Study Diurnal Cycles of Tropical Winds

This paper presents a combined active/passive ocean vector wind (OVW) retrieval from the Global Precipitation Measurement Core Observatory (GPM-CO). Although the GPM-CO was designed to observe global precipitation, we demonstrate the potential for providing a climate quality OVW data product for the multi-decade GPM- TRMM era. Development of GMFs for the Ku- and Ka-band dual frequency Precipitation Radar (DPR) and the GPM Microwave Imager (GMI) remote sensors onboard the GPM-CO is presented. The unique GPM active/passive OVW retrieval algorithm is described, which uses the modified 2nd Stokes parameter (linear combination of V & H-pol Tb's) to cancel the atmosphere and to enhances the anisotropic WD signal superimposed on GMI Tbs. The PR and GMI GMF's were then combined in a maximum likelihood estimation (MLE) algorithm to infer the OVW. Finally, this OVW retrieval algorithm was validated by comparing retrievals with collocated NASA Advanced Scatterometer (ASCAT) wind vectors. The statistics of WS and WD retrieval accuracy performance are presented and are shown to be comparable with those of conventional scatterometer and polarimetric radiometer missions.