Validation of wind vector retrieval from ENVISAT ASAR images

Ocean wind speeds and wind directions are estimated simultaneously using the normalized radar cross sections corresponding to two neighboring images, having slightly different incidence angles. The wind direction ambiguity is removed by using the direction closest to that given by the buoy or some other determination. To validate this method, some ENVISAT ASAR images of the Gulf of Mexico and coastal waters of the North Atlantic are used to estimate wind vectors, compared with wind measurements from buoy data. Moreover, ASAR can also provide dual-polarization SAR images. Therefore, we derived an empirical polarization ratio as a function of the radar incidence angle. Wind vector fields are retrieved from RADARSAT-1 SAR HH-polarization images based upon this empirical ratio and compared with buoy measurements and QuikSCAT data