WindSal is the first spaceborne fully polarimetric radiometer. It measures all four Stokes components; Tv (vertically polarized), Th (horizontally), U (difference between polarizations at +45° and -45°) and V (difference right hand minus left hand circular polarized) and is primarily developed to retrieve wind speed and direction over ocean. Here we investigate the WindSat observations over Dome C, Antarctica, consisting of nearly flat terrain at about 3200 m above sea level. The seasonal cycles of Tv and Th reflect the surface temperature cycle and the penetration depth decreasing with increasing frequency (6 to 37 GHz), while the difference Tv -Th is nearly constant. The U and V signals are most pronounced in Austral winter (July-August). The differences between ascending and descending overpasses, corresponding to different azimuth observing directions, take values up to 1.2 K (U) and 3 K (V). Fitting the data of for and aft swath to a second order harmonic function of the azimuth angle reveals a consistent orientation of the structures at the used frequencies 10 and 37 GHz and Stokes components U and V in the direction of about 153° with respect to north, consistent with the small overall slope direction of the terrain (145°) and ERS scalterometer observations.
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