Development of a global scatterometer validation and monitoring

Stoffelen et al. (2006) look for the most appropriate scatterometer wind-to-stress transformation in order to produce a ocean stress product in the tropics. To study the impact of large wind variability and waves on the wind-to-stress transformation, the work of Stoffelen et al. (2006) is repeated here using an extra-tropical dataset. A comparison between two commonly used Surface Layer (SL) models, i.e., LKB and ECMWF, is performed. Since the ECMWF roughness parameterization is sea state dependent, its Charnock parameter is variable, in particular in the extra-tropics. A relevant result of this comparison is that the bias due to the difference in the default Charnock values of both models remains the same when variable Charnock input is used for ECMWF SL model, indicating that Charnock (sea state) effects are rather small in terms of stress. We confirm that an independent ERS scatterometer stress (SOS) product can be obtained by adding 0.7 m/s to CMOD-5 wind and use such result as the 10-m neutral wind input to a recently developed SL model, which is subsequently needed to compute stress.