Non-resonant mechanisms of radar signal scattering from the sea surface

摘要

The main non-resonant (non-Bragg) mechanisms of microwave backscattering from the sea surface are described, which are backscatter from large scale breaking gravity waves and backscatter from the steep wavelets of meso-scale spectrum (meso-waves). The important features of the non-resonant scattering at low grazing angles, which principally can not be explained by the commonly accepted resonant theory are abnormal polarization ratio, upwind-down wind asymmetry and presence of strong spikes. For interpretation of the observed data extended composite model of the sea surface is suggested. In contrast to the standard two scale composite model, based on the Bragg theory, extended composite model involves the non-resonant components, describing contribution of the large scale breaking waves ("macro-breaking") and contribution of the sharp-crested waves of the meso-scale (decimeter) spectrum ("micro-breaking"). The paper intend to stimulate analyzing the angular, frequency and polarization characteristics for the both non-resonant mechanisms and thereby to reveal specific signatures of each mechanism.