Surface marine wind retrieval in non-precipitating regions

Error estimates for the surface winds retrieved from Radarsat-1 synthetic aperture radar (SAR) backscatter cross section are derived using nonlinear regression. The SAR-wind relationship employed is the European Remote Sensing (ERS) C-Band model (CMOD) and the polarization ratio of Vachon and Dobson (2000). Non-precipitating regions of the SAR acquisitions obtained during the past 15 months along the east and west coasts of North America are considered. Bias and variance of the errors in backscatter cross section, relative to the wind errors of a high-resolution numerical model, are iteratively estimated in preparation for SAR data assimilation. An offline combination of these two data yields retrieved winds that are comparable to in situ observations from ships of opportunity and buoys. Assuming no errors in the latter observations, improvements over the model winds are quantified.