SAR海洋内波表层流反演方法探讨

基于海洋内波SAR成像机理与M4S海面微波散射成像模型,提出SAR海洋内波表层流反演新方法。首先从SAR图像上获得内波剖面的海面后向散射强度,利用AH理论的线性近似关系得到猜测表层流,通过海面微波散射成像模型仿真海洋内波的SAR海面后向散射强度,利用二分法不断地修改风速和流速梯度等参数,使仿真信号最大程度的逼近实际SAR图像上的海面后向散射强度,输出最终海表层流。以中国南海海区3景海洋内波SAR图像为例,对该方法进行了探讨。结果表明,仿真的海洋内波SAR海面后向散射强度剖面和实际SAR图像上的信号剖面吻合,两者的相关系数达90%以上,说明该反演方法是收敛与可行的。

Retrieving internal wave surface currents from SAR image

Based on ocean internal wave Synthetic Aperture Radar (SAR) imaging mechanism and the M4S model, which was applied to simulate the oceanic features of ocean surface, one new method for retrieving internal wave surface currents from SAR image is introduced. Firstly, according to the AH linear theory, the first guessed surface currents could be estimated from the normalized radar crossing section (NRCS) of the internal wave profile in SAR image, and the signal induced by internal wave surface currents can be simulated by M4S. Then the wind speed and internal wave surface currents gradients are modified using the dichotomy method step by step, which causes the simulated signal close to the NRCS measured from SAR image. Finally, the wind speed and the surface currents could be retrieved until a satisfied match between the simulated signals and SAR images. This method is tested on three ERS-2 SAR images in the South China Sea. The results show that the simulated internal wave signal is consistent with the NRCS of internal wave SAR images. Their correlation coefficients are up to 90%, which indicate that this method is convergent and applicable.