背景场对变分方法海面风速反演结果的影响

Influence of background wind field on the inversion results of sea surface wind speed evaluated with variational method

利用前期提出的合成孔径雷达反演海面风场变分方法新解法,开展背景场对合成孔径雷达反演海面风场变分方法风速反演结果影响的模拟试验分析。模拟试验表明,变分方法有效解决了直接反演方法的两大缺陷:一是当背景场风速较大的时候,合成孔径雷达后向散射系数对风速不敏感,直接导致较大的风速反演误差;二是当背景场风向存在误差时,将导致后向散射系数更大的误差,进而导致风速反演结果更大的误差。进一步试验表明,当背景场风速较大时,变分方法风速误差低于直接反演方法风速误差。而当背景场风向误差较小时,直接反演方法风速误差比变分方法风速误差小。

The background wind field influence is evaluated with a new agorithm of synthetic aperture radar variational wind retrieval method that we put forward recently.Simulation results reveal that the first disadvantage of the direct inversion method is that when the background wind speed is high,the synthetic aperture radar normalized radar cross section is not sensitive to wind speed which leads to large wind speed errors.The second disadvantage is that when the background wind directions have errors,the normalized radar cross section will have larger errors,which will further result in larger wind speed errors.The variational method overcomes these two disadvantages.Forwardly,when the background wind speed is high,the variational wind speed errors are smaller than that of the direct method.But when the background wind direction is small,the direct wind speed errors are smaller than the variational wind speed errors.When the wind direction error of the background field is small,the wind speed error of the direct inversion method is smaller than that of the variational method.