Modified Two-Scale Model for Better Prediction of the Up/Down Wind Asymmetry in Radar Backscattering from the Ocean Surface

Abstract

The upwind-downwind asymmetry in radar return from the sea surface is well known. This paper develops a modified two-scale model to better describe the difference between upwind and downwind of the radar backscatter at moderate incidence angles caused by skewness of the non-Gaussian sea surface. The unknown parameter in the modified model is estimated by fitting the model to CMOD5.n at different incidence angles under various wind conditions. Then the modified model is compared with CMOD5.n and the advanced scatterometer (ASCAT) backscatter measurements. The results show that the model predictions are in rather good agreement with the reference data. The modified model can accurately describe the difference between the upwind and downwind normalized radar cross section (NRCS) with the root mean square difference being about 0.02 dB compared with that of CMOD5.n.