The Transition From Weak to Strong Diffuse Radar Bistatic Scattering From Rough Ocean Surface

Abstract

Many of the currently used models of scattering from a rough ocean surface are designed for the regime of strong diffuse scattering that takes place at large Rayleigh parameter Ra . Using them for the case of weak, or even moderate diffuse scattering that is characterized by Ra ≲ 1 would lead to an incorrect result. At the same time, for practical applications it is important to describe the transition from partially-coherent scattering to completely non-coherent, strong diffuse scattering in terms of the bistatic radar cross section σ0. This situation may occur for scattering of GNSS signals or other signals of opportunity from a rough ocean surface under weak winds, or from ice. In this paper, we obtain an expression for σ0 for the case of weak-to-moderate diffuse scattering using a formulation based on the small slope approximation of the first order (SSA1). For a reasonable range of Ra , calculations can be quickly performed using standard desktop computers. We demonstrate results of such calculations for bistatic radar scattering for L-band at lowto-moderate Ra and its transition to σ0 at large values of Ra.