Surface roughness and breaking wave properties retrieved from polarimetric microwave radar backscattering

Abstract

Ocean surface roughness and wave breaking are the two main contributors of radar backscattering from the ocean surface. The relative weightings of the two contributions vary with the microwave polarization: the VV (vertical transmit vertical receive) is dominated by the Bragg resonance scattering mechanism, and the HH (horizontal transmit horizontal receive) and VH (horizontal transmit vertical receive or vertical transmit horizontal receive) contain nontrivial non-Bragg contributions mainly produced by breaking features. A method is developed to obtain the short-scale properties of ocean surface roughness and wave breaking from Ku, C, and L band polarimetric sea returns. The results are used for quantitative evaluation of the ocean surface roughness spectral models and for deriving understanding of the breaking contribution important to microwave ocean remote sensing, in particular its dependence on wind speed, microwave frequency, and incidence angle. Implications of the results to air-sea interaction applications are discussed.