Quality Assessment of Envisat Asar Wave Mode Products Based on Regional and Seasonal Comparisons with Wam Model Outputs

RESUME Since january 2003, ASAR Wave mode products have been systematically monitored. Quality assessment reveals that calibration issue still remains unsolved and unexpected computational error arising on WVS products. Furthermore, systematic regional and seasonal comparisons with collocated parameters of the numerical wave model WAM as provided by ECMWF exhibit a global good agreement with WAM outputs in terms of significant wave height (SWH). Yet, specific limitations are due to wind dependency on SAR imaging mechanisms. SARderived SWH is underestimated under high sea state conditions due to well-known azimuthal low pass filtering. Under low wind conditions, WV products tend to overestimate SWH due to underestimation of CMOD-derived Tilt modulation transfer function. Promising results on Doppler centroid analysis are also presented.