Sea surface wind directions retrieval method based on footprints of rain cells on SAR images
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摘要: 利用地球物理模式函数进行SAR海面风速反演时,需以风向作为地球物理模式函数的输入。本文应用了一种利用SAR图像上雨团足印顺风一侧比逆风一侧明亮的图像特征的海面风向提取方法,以进行海面风速反演。4景RADARSAT-2卫星SAR示例数据风向提取结果相对于ASCAT散射计的风向均方根误差满足不大于16°。分别以本文方法提取的风向和ASCAT散射计风向作为输入,利用地球物理模式函数CMOD5进行海面风速的SAR反演,两者的风速反演结果基本一致,其均方根误差差值不超过0.3 m/s。本文利用SAR图像雨团足印信息的风向提取方法准确可靠,可应用于SAR海面风速反演。Abstract: Wind directions are necessary to sea surface wind speed retrieval from SAR image by Geophysical Model Function (GMF). In this paper, a method of sea wind directions retrieval from SAR images by using the feature of footprints of rain cells on SAR image with brighter in downwind direction and darker in upwind direction is applied on sea surface wind retrieval. The root mean square errors (RMSE) of wind directions retrieved from 4 case studied RADARSAT-2 SAR images compared with wind directions of ASCAT are all less than 16 degrees. The wind speed retrieval results from these 4 SAR images by using GMF of CMOD5 with wind directions retrieved from rain cells are nearly the same as that with wind directions of ASCAT scatterometer, the differences of RMSEs are no more than 0.3 m/s. The method of wind directions retrieval from the feature of rain cell footprints on SAR image developed in this paper can be applied in SAR wind speeds retrieval.
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Key words:
- rain cells /
- SAR /
- wind directions /
- sea surface wind speed retrieval
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