基于SAR图像速度聚束调制的海浪反演研究

本文首先对合成孔径雷达（SAR）海浪成像中的3种调制（倾斜调制、流体力学调制与速度聚束调制）的影响进行了对比分析，结果显示:速度聚束调制对SAR图像的影响最为显著。另外，由于SAR图像中固有相干斑噪声的存在，较低波数范围的噪声难以滤除或抑制，利用经典MPI方法反演海浪谱会造成低波数范围谱值偏大。基于此，本文借鉴经典MPI海浪谱反演算法，建立了基于速度聚束调制的海浪方位向斜率谱和有效波高的反演算法。通过将经典MPI方法、同极化调制法及本文算法等3种海浪反演方法所得有效波高与浮标数据进行比较，结果显示:本文方法反演得到的海浪有效波高与浮标数据获得的有效波高之间的均方误差为0.79 m，为3种方法中最小。

Ocean wave inversion based on the velocity bunching modulation of SAR image

The effects of three kinds of modulation (the tilt modulation, the hydrodynamic modulation and the velocity bunching modulation) on sea wave SAR (synthetic aperture radar) image are compared and analyzed firstly. The results show that the velocity bunching modulation has the most significant effect on SAR images. In addition, due to the inherent speckle noise in the SAR image, it is difficult to filter or suppress the noise in the range of low wavenumber. And the inversion of wave spectrum by classical MPI (max-planck institute) method will result in the larger spectral value in the range of low wavenumber. Referring to the classical MPI inversion algorithm, an azimuth slope spectrum and SWH (significant wave height) inversion algorithm based on the velocity bunching modulation are proposed in this paper. Comparing the SWH obtained by the classical MPI method, the co-polarization modulation method and the algorithm proposed in this paper with the buoy data, one can find that the mean square error between the SWH retrieved by the algorithm proposed in this paper and the SWH obtained from buoy data is 0.79 m, which is the smallest among the three methods.