An Investigation of Non-Bragg Scattering from the Sea Surface

Abstract

Grant Number: N00014-01-1-0153 http://www.apl.washington.edu LONG-TERM GOALSThe long-range objective of this work is to develop a detailed characterization of non-Bragg scattering from a wind-roughened water surface, or a breaking wave region, and establish a link between radar observations and physical processes, leading ultimately to a more complete, physically-based model for predicting radar scattering from the sea surface. OBJECTIVESOur objective is to characterize non-Bragg scattering from the air-sea interface as a function of environmental conditions and radar parameters to improve our understanding of the mechanisms responsible for non-Bragg sea surface scattering and to develop models appropriate for this type of scattering. Most predictive models of radar backscattering from the sea surface rely on Bragg-based characterization of sea surface scattering. Evidence suggests that although Bragg scattering from the sea surface accounts well for many observations, some phenomena exist that it is unable to explain, indicating that it does not adequately represent all of the physical processes. A physically-based model of sea surface scattering that takes into account both Bragg and non-Bragg scattering will ameliorate this situation. APPROACHOur approach is to study non-Bragg scattering from the air-sea interface using existing data sets that include both environmental and radar measurements. Our investigations focus on the following issues:Non-Bragg Criterion. The ratio of normalized radar backscatter from the roughened water surface