ABSTRACT

The Synthetic Aperture Radar (SAR) carried on-board satellites yields invaluable data of global wave spectra since the early 1990s, with several satellites in orbit at present and more launches scheduled in the near future. However, the retrieval of wave information from SAR images constitutes a complex set of procedures. In this context, we have presented here a methodology to simulate SAR image spectra of ocean swell waves. SAR simulators are important tools for the implementation and evaluation of wave spectra retrieval schemes. The one proposed here is based on the Hasselmann Transform whose Modulation Transfer Functions (MTF’s) account for the main physical processes involved in the imaging of ocean waves. A detailed description of its structure is provided. Through several test cases, we highlight some particularities of the relationship between SAR image spectra and wave spectra. We have evaluated the impact of the parameters settings and input information on the retrieval process, pinpointing possible shortcomings. The results indicated that useful information about the processes involved in the imaging of ocean swells can be derived from the SAR simulator.

摘要

自1990年代初以来，合成孔径雷达（SAR）携带的机载卫星就产生了不可估量的全球波谱数据，目前有几颗卫星在轨，并计划在不久的将来发射更多卫星。但是，从SAR图像中检索波信息构成了一组复杂的过程。在这种情况下，我们在这里提出了一种模拟海洋涌浪的SAR图像光谱的方法。SAR模拟器是实现和评估波谱检索方案的重要工具。这里提出的一个基于哈塞尔曼变换，其调制传递函数（MTF）解释了海浪成像中涉及的主要物理过程。提供其结构的详细描述。通过几个测试用例，我们重点介绍了SAR图像光谱和波谱之间关系的一些特殊性。我们评估了参数设置和输入信息对检索过程的影响，指出了可能存在的缺陷。结果表明，可以从SAR模拟器中获得有关海浪成像过程的有用信息。