Ocean surface wind retrievals using the TRMM microwave imager

An analysis of one year of brightness temperature data from the TRMM microwave imager (TMI) is presented with regard to the retrieval of ocean surface wind speeds using standard regression techniques with in situ meteorological buoy measurements. Comparisons to similar satellite radiometer data from the special sensor microwave/imager (SSM/I) are also presented to help quantify atmospheric contributions to the surface wind retrievals. Particular emphasis is placed upon the use of the 10.7 GHz channels aboard the TMI in overcoming the contamination in the ocean surface brightness temperature measurements caused by precipitation and water vapor in the propagation path. The resulting wind retrieval improvements permit a relaxation in the rain flag definitions used to determine precipitation interference cutoff criteria, allowing accurate wind speed retrievals over a wider range of precipitation conditions. These improvements are realized through the construction of a new D-matrix wind speed retrieval algorithm suitable for the middle and low latitude coverage provided by the TRMM orbit.