A geophysical model function for WindSat polarimetric radiometer wind retrievals using linear polarizations

In this paper, we develop a novel geophysical model function (GMF) for the WindSat radiometer relating the vertically (V-pol) and horizontally (H-pol) polarized brightness temperature (T_B) to the ocean surface wind field. The brightness temperature data from the 10, 18 and 37 GHz channels were used in this analysis. The brightness temperature combination of the form (AV-H) is found to be mostly independent of the atmospheric variations, where A is a constant number for each frequency. The GMF was developed empirically using the collocated wind vectors from the QuikSCAT scatterometer retrieval as truth and the WindSat's (AV-H) T_B's. We examined the characteristic of the GMF and explored the opportunity to improve our current WindSat wind direction retrieval that utilizes only 3^rd and 4^th Stokes measurements, by integrating this GMF. The strength of the wind directional signals is encouraging for moderate wind speed at 8 m/s and higher.