On the polarization-dependent signatures of atmospheric and oceanic features in radar images of the ocean surface

Abstract

Multi-polarization radar images of the ocean surface from various experimental campaigns suggest that the backscattered signal is more sensitive to wind field variations at vertical (VV) than at horizontal (HH) polarization. On the other hand, radar signatures of oceanic features like internal waves or underwater bottom topography are often better visible at HH. In this paper, a possible theoretical explanation for these phenomena is discussed. It is shown that polarization-dependent radar signatures are qualitatively consistent with predictions of a composite surface scattering model, where the ratio between modulation depths at HH and VV is determined by the intensity variations of ocean waves in different wave-number ranges. Using a simple scenario of wind and current variations, it is demonstrated that a pair of radar images with dominant oceanic and atmospheric signatures at HH and VV, respectively, can be basically obtained from the model.