VECTOR RETRIEVAL USING ERS-1 SYNTHETIC-APERTURE RADAR IMAGERY

An automated algorithm intended for operational use is developed and t ested for estimating wind speed and direction using ERS-1 SAR imagery, The wind direction comes from the orientation of low frequency, linea r signatures in the SAR imagery that we believe are manifestations of roll vortices within the planetary boundary layer, The wind direction thus has inherently a 180 degrees ambiguity since only a single SAR im age is used, Wind speed is estimated by using a new algorithm that uti lizes both the estimated wind direction and sigma(o) values to invert radar cross section models, We show that: 1) on average the direction of the roll vortices signatures is approximately 11 degrees to the rig ht of the surface wind direction and can be used to estimate the surfa ce wind direction to within +/-19 degrees and 2) utilizing these estim ated wind directions from the SAR imagery subsequently improves wind s peed estimation, generating errors of approximately +/-1,2 m/s, for ER S-1 SAR data collected during the Norwegian Continental Shelf Experime nt in 1991.