A model for ocean wave imaging by a single pass cross track interferometric SAR (InSAR)-the SINEWAVE experiment

Abstract

So far spaceborne SAR are the only all weather systems to provide directional ocean wave information on a continuos and global basis. However some care must be taken using SAR data to derive 2D ocean wave spectra; basic SAR principles cause unrecoverable information loss in the imaging process, and incomplete understanding of ocean wave imaging mechanisms leads to unsatisfactory exploitation of SAR data. The common approach to deal with the problem of information loss in the SAR image spectrum, is the use of an inversion algorithm taking some a priori knowledge, e.g. from wave models, S. Hasselmann et al. (1996). One goal of the present study is to address the second problem and to improve the understanding of SAR ocean wave imaging. In the following the authors investigate the ocean wave imaging mechanisms of a cross track InSAR system, which uses two SAR antennas with baseline perpendicular to the flight direction. In contrast to along track InSAR systems, which have been used, for example, to measure ocean currents, a cross track InSAR is able to measure topography. This is done by using the phase difference, of the radar signals, which are transmitted and received by the two antennas in turn. As the system yields simultaneous measurements of the sea surface elevation and the corresponding radar cross section, it is an ideal tool to investigate the ocean wave imaging by conventional SAR.