| 摘要: |
| 合成孔径雷达（SAR）海面场景原始数据仿真是研究海洋动力参数（表面波浪、风矢量和洋流）的有效工具。目前海面场景原始数据仿真方法已经基于逆Omega-K算法实现了海洋运动参数的空间变化。但是目前仅仅讨论了正侧视情况下的海面场景仿真，应用范围有限，同时没有考虑Stokes漂流以及Bragg相速度的影响，而这两者都是存在于真实海面的。通常情况下为了反演得到海面流场的二维速度矢量，雷达需要从两个不同的方位方向观察海面的同一个区域，因此这就需要考虑大斜视的雷达波束，同时Stokes漂流和Bragg相速度是SAR海表面流场观测不容忽视的两种运动。本文在不改变原有正侧视逆Omega-K算法的情况下，通过增加重新计算零方位时刻的斜视波束中心位置坐标，并据此确定SAR原始数据在多普勒域的位置来将其扩展到大斜侧视逆Omega-K算法，并通过时域Stokes漂流公式到频域内离散化Stokes漂流公式的推导来加入Stokes漂流，以及根据Bragg散射机制加入了Bragg相速度。仿真结果表明，经过聚焦成像后的SAR图像很好的体现了真实海面波浪场的形状，同时能够很好地反演出设定的雷达径向流场速度，且流速精度误差控制在6%以内。最后也证明了Bragg相速度以及Stokes漂流对于海面流场的影响不可忽视。 |
| 关键词: 大斜侧视 仿真 逆Omega-K Stokes漂流 |
| DOI：10.11693/hyhz20180900226 |
| 分类号:P731 |
| 基金项目:国家重点研发计划项目，2016YFC1401002号；国家自然科学基金项目，41606201号，41620104003号，41576173号；国家自然科学基金青年项目，41706202号；江苏省高校自然科学研究面上项目，17KJB170017号。 |
附件 |
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| AN IMPROVED RAW DATA SIMULATION METHOD FOR MEASURING OCEAN SURFACE CURRENT |
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DUAN He-Yang, LIU Bao-Chang, HE Yi-Jun, LI Xiu-Zhong
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Nanjing University of Information Science & Technology, Nanjing 210044, China
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| Abstract: |
| Synthetic Aperture Radar (SAR) raw data simulation of ocean surface is an effective tool for studying ocean surface waves and currents. At present, the raw data simulation method of ocean surface has been realized with the spatial variation of ocean motion parameters based on the inverse Omega-K algorithm. However, only the side-looking simulation of sea scene is currently discussed. The application scope is limited, and the Stokes drift and Bragg phase velocity are not be considered simultaneously. Generally, for example, in order to retrieve a two-dimensional velocity vector of the sea surface current field, the radar needs to observe the same area of the sea surface from two different directions; therefore, a large squint-looking radar beam is needed. At the same time, Stokes drift and Bragg phase velocity are two movements that cannot be ignored in SAR sea surface observation. Without changing the original side-looking inverse Omega-K algorithm, we grafted the side-looking SAR raw data into the large squint side-looking inverse Omega-K algorithm by adding the strabismus beam center position coordinates at the zero-azimuth moment and determining the position of the original SAR data in the Doppler domain, and adds Stokes drift and Bragg phase velocity. The results show that the hypothetical current field can be well inversed and the accuracy can satisfy the requirements. The focused SAR image reflects the shape of the sea surface wave field very well. |
| Key words: large squint side-looking simulation inverse-omega-K Stokes drift |
