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为了提高星载雷达高度计海面风速产品的精度并更好地修正海况偏差的影响,有必要对高度计测量的后向散射系数进行定标。分布目标是星载雷达散射系数定标的有效手段,而沙漠的散射特性特别适于高度计的散射系数定标。检验了Jason-2卫星高度计的沙漠回波波形,在澳大利亚辛普森沙漠和我国的塔克拉玛干沙漠选取了适当的区域,收集了在这些区域长达7a的Jason-2高度计数据。基于这些数据,研究了Jason-2卫星雷达高度计在沙漠上的散射系数特性,并提出了基于沙漠的散射系数定标方法,分析了其原理、可行性和试验方案,探讨了高度计和现场定标散射计足迹匹配等关键技术,并对其定标误差进行了分析,论证了沙漠定标场可实现优于0.5dB的定标精度。该方法有助于进一步提升海洋2号(HY-2A)卫星风速和海况偏差产品的质量和应用前景。
In order to improve the precision of the sea surface wind speed products of the spaceborne radar altimeter and to better correct the influence of the sea state deviation, it is necessary to calibrate the backscatter coefficient of the altimeter measurement. The distribution target is an effective means to calibrate the spaceborne radar scattering coefficient, while the scattering characteristic of the desert is particularly suitable for the calibration of the scattering coefficient of the altimeter. The Jason-2 satellite altimeter desert echo waveforms were examined and the appropriate areas were selected in the Simpson Desert, Australia and the Taklamakan Desert of our country, collecting Jason-2 altimetry data up to 7a in these areas. Based on these data, the scattering coefficient characteristics of Jason-2 satellite radar altimeter in the desert were studied, and the desertification-based scattering coefficient calibration method was proposed. The principle, feasibility and test scheme were analyzed. The altimeter and on-site calibration Scatterometer footprint matching and other key technologies, and its calibration error analysis demonstrated that the calibration field can achieve better than 0.5dB calibration accuracy. This method helps to further improve the quality and application prospects of HY-2A satellite wind speed and sea-state deviation products.