Two-dimensional sea surface current field inversion based on SAR sub-aperture decomposition
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摘要: 对Radarsat-2和Sentinel-1A分别观测的两个海域的单景SAR图像进行子孔径分解，各自得到不同方位角上的两幅SAR子孔径图像。使用多普勒质心频移法分别对不同方位角的两幅SAR图像进行海流反演，并进行海流矢量合成，采用经过时空匹配的HYCOM模式数据对反演结果进行检验，结果表明：Radarsat-2观测的SAR图像分解的两幅子孔径SAR图像矢量合成后的海流与HYCOM模式数据相比，速度均方根值为0.09 m/s，相关系数为0.64；方向均方根值为10.49°，相关系数为0.78。Sentinel-1A观测的SAR图像分解的两幅子孔径SAR图像矢量合成后的海流与HYCOM模式数据相比，速度均方根值为0.06 m/s，相关系数为0.82；方向均方根值为2.85°，相关系数为0.86。由此可见，基于单景SAR分解的两幅子孔径SAR图像可以有效反演二维海流。其反演精度与雷达视向和真实海流矢量的方向有关，二者的角度越小，反演海流矢量的精度越高。Abstract: Two single-scene SAR images observed by Radarsat-2 and Sentinel-1A were decomposed to obtain a pair of SAR sub-aperture images at different azimuth-angles, respectively. Doppler centroid anomaly method was used to invert the sea surface current of two sub-aperture images with different azimuth angles. The current field was obtained by vector synthesis. The inversion results were verified by the HYCOM model data with spatio-temporal matching. The results show that the root mean square (RMS) of the current velocity between the synthesized result by two sub-aperture images of Radarsat-2 and the HYCOM model data is 0.09 m/s, and the correlation coefficient is 0.64. The RMS of current direction is 10.49° and the correlation coefficient is 0.78 of this group data. As for the results of the Sentinel-1A image, the RMS of the current velocity is 0.06 m/s, and the correlation coefficient is 0.82. The RMS of the current direction is 2.85°, and the correlation coefficient is 0.86. It can be seen that the two-dimensional ocean currents field can be effectively inverted based on the two sub-aperture SAR images that decomposed from single-scene SAR image. The inversion accuracy is related to the relative direction of the radar’s looking direction and the real current vector. The inversion accuracy of the sea surface current field can be higher when the relative angle is small.
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Key words:
- SAR /
- sub-aperture /
- Doppler centroid anomaly /
- two-dimensional current field /
- HYCOM
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图 3 Radarsat-2卫星全孔径SAR强度图
Fig. 3 Full-aperture SAR intensity image of Radarsat-2 satellite
图 4 Sentinel-1A卫星全孔径SAR强度图
Fig. 4 Full-aperture SAR intensity image of Sentinel-1A satellite
图 8 SAR反演的海流矢量与HYCOM海流矢量对比图
Fig. 8 Comparison diagram of SAR inverted current vector and HYCOM current vector
图 10 SAR反演的海流矢量与HYCOM海流矢量对比图
Fig. 10 Comparison diagram of SAR inverted current vector and HYCOM current vector
图 11 合成海流矢量与HYCOM值相关散点图
Fig. 11 Scatter plots of synthesized current vector and HYCOM values
表 1 反演海流矢量与HYCOM值统计结果
Tab. 1 Statistical results of inverted current vector and HYCOM values
速度 方向 平均偏差 −0.08 m/s 9.98° 均方根差 0.09 m/s 10.49° 相关系数 0.64 0.78 
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表 2 合成海流矢量与HYCOM值统计结果
Tab. 2 Statistical results of synthesized current vector and HYCOM values
速度 方向 平均偏差 −0.05 m/s 2.72° 均方根差 0.06 m/s 2.85° 相关系数 0.82 0.86
下载: 导出CSV
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