A Volume-Surface Composite Scattering Model for Nonlinear Ocean Surface With Breaking Waves and Foam Layers Under High Wind Conditions

Abstract

Electromagnetic scattering from the sea surface is of great significance in ocean remote sensing especially under high wind conditions. A novel volume-surface composite scattering model of nonlinear rough sea surfaces with breaking waves and foam layers under high wind conditions is presented in this study. Based on the semi-deterministic facet scattering model (SDFSM), using a ray tracing method combined with impedance equivalent edge currents (RT-IEEC) and vector radiative transfer theory (VRT), the backscattering characteristics of the sea surface with breaking waves and foam layers are investigated. The crest-and static-foam coverage was introduced to determine the breaking point and foam coverage distribution. The dependence of the backscattering coefficient of the sea surface with and without breaking waves and foam layers on the incident angle, wind speed, and the polarization are discussed in detail. The results of numerical simulations are analyzed and compared with the measured data from the relevant references which verifies the validity of our volume-surface composite scattering model. The synthetic aperture radar (SAR) image simulations of the surface with and without the breaking waves and foam layers are compared, and the combined effects of the breaking waves and whitecaps are analyzed.

Modeling and SAR imaging of the sea surface: A review of the state-of-the-art with simulations

“…For the specular reflection region, with incidence angles about 0 • ∼ 20 • , the Kirchoff Approximation (KA) [20], also known as the Physical Optics (PO) method, has been developed. The contribution of breaking waves in a normalized radar crosssection (NRCS) has been investigated in numerous works [19], [21]- [24]. At moderate incidence angles (20 • ∼ 70 • for VV, and 20 • ∼ 60 • for HH polarization), the dominant mechanism is Bragg scattering.…”