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针对基于散射计地球物理模型函数的机载合成孔径雷达(SAR)海面风场反演中存在的风向获取依赖于图像风条纹或数值预报、散射计数据和浮标等背景场资料,风向与SAR图像时空分辨率不匹配,进而影响机载SAR海面风场反演精度等问题,本文根据机载SAR对海探测特点,研究一种适用于C波段机载SAR的海面风场反演新方法.利用SAR图像距离向不同入射角的后向散射系数,依据地球物理模型构造最小代价函数,通过代价函数的求解直接从机载SAR数据同时反演出海面风速和风向.利用论文提出的海面风场反演方法分别对仿真SAR数据和实测C波段机载SAR数据进行风向、风速的反演误差分析及试验验证.研究结果表明,该方法适用于机载SAR海面风场反演,可不依赖背景风向直接反演出精度较高的风速和风向;雷达后向散射系数误差是决定海面风速、风向反演精度的关键因素,辐射定标精度越高则反演误差越小;海面风速反演误差随着风速的提高而增大,当海面风速大于18m/s时,风速反演误差显著增加,而海面风向的反演误差与风速无明显关系.
The acquisition of wind direction in the wind field inversion of airborne Synthetic Aperture Radar (SAR) based on the scatterometer geophysical model functions depends on the image wind streaks or numerical predictions, scatterometer data and buoy background data, wind direction and SAR image The spatial and temporal resolution mismatch, which will affect the retrieval precision of airborne wind field over the airborne SAR.A new method of sea surface wind inversion suitable for C-band airborne SAR is proposed based on the characteristics of airborne SAR detection The backscattering coefficient of SAR images from different angles of incidence was calculated and the minimum cost function was constructed according to the geophysical model. The sea surface wind speed and direction were directly retrieved from the airborne SAR data by solving the cost function. Methods The error analysis and experimental verification of the wind direction and wind speed of the simulation SAR data and the measured C-band airborne SAR data were carried out respectively.The results show that the proposed method is suitable for the inversion of the sea surface wind field over the airborne SAR without depending on the direct wind direction The wind speed and wind direction with high performance precision; the error of backscatter coefficient of radar is the key factor that determines the wind speed and wind direction inversion accuracy; The higher the accuracy is, the smaller the inversion error is. The error of sea surface wind velocity inversion increases with the increase of wind velocity. When the wind velocity of sea surface is more than 18m / s, the error of wind velocity inversion increases significantly, while the error of wind direction inversion and wind speed Obvious relationship.