ABSTRACT

The patterns of internal waves are common occurrences in remote sensing images of the ocean. Internal waves are usually induced by undulating terrain on the sea floor or moving sources in the stratified ocean, especially in an offshore sea or straits in which there exists a relatively significant density stratification of the seawater. In this paper, a new method for simulating the synthetic aperture radar (SAR) images of the internal wave wake excited by underwater vehicles is presented. The flow field of the wake is solved directly using the Reynolds averaged Navier–Stokes solver, and the ambient waves on the sea surface are considered as random wind waves. To consider a continuously stratified ocean, a special multiphase flow model is implemented, which can be used to obtain arbitrary stratified structures numerically. To estimate the scattering distribution of the wakes on the sea surface, an improved facet scattering model is proposed, in which the hydrodynamic modulation of the ambient waves by the wake is considered. Based on the results calculated by the scattering model, the velocity-bunching integral is implemented to simulate the intensity of SAR images of a disturbed sea surface having embedded internal wave wakes.

摘要

内波模式在海洋遥感图像中很常见。内波通常是由海底起伏的地形或分层海洋中的移动源引起的，特别是在近海海域或存在相对显着的海水密度分层的海峡中。本文提出了一种模拟水下航行器激发的内波尾流合成孔径雷达（SAR）图像的新方法。尾流流场采用雷诺平均 Navier-Stokes 求解器直接求解，海面环境波视为随机风波。为了考虑连续分层的海洋，实现了一种特殊的多相流模型，可用于数值获取任意分层结构。为了估计海面尾流的散射分布，提出了一种改进的面散射模型，其中考虑了尾流对环境波的水动力调制。在散射模型计算结果的基础上，采用速度集束积分法模拟了嵌入内波尾迹的受扰海面的SAR图像强度。