Sensitivity of modeled polarimetric radar ocean scattering to wind direction

The results of airborne and satellite polarimetric radar experiments at Ku- and C-bands indicate that the sensitivity of cross-polarized signals persists for high wind speed when the co-polarized signals saturate. It was found that the cross-polarized return is also sensitive to the anisotropy of the wind-driven waves. Here, our intention is to analyze how well the available theoretical models can reproduce the azimuthal angle behavior of polarimetric radar signals. We calculated the fully polarimetric normalized radar cross section using the numerical code based on a small slope approximation of the second order. These calculations are performed for Ku- and C-bands and for two semi-empirical ocean spectral models. Results are compared with the available experimental data obtained from airborne and satellite platforms. The differences between the theoretical curves and experimental data suggest that some additional contribution, presumably from scattering by steep and breaking waves, needs to be accounted for.