中法海洋卫星微波散射计在轨性能验证

Orbit Performances Validation for CFOSAT Scatterometer

中法海洋卫星(CFOSAT)微波散射计是国际上第一个旋转扇形波束体制散射计,通过优化雷达观测几何实现对地面目标多角度和多方位的高精度测量,提高海面风场、土壤湿度和海冰面积等地球物理参数的反演精度.根据CFOSAT卫星2018年10月发射以来的在轨测试数据,结合散射计系统特点,分析验证了星上定标数据和后向散射系数反演结果的正确性,并对CFOSAT首批科学数据进行了定量分析和系统评价.结果表明,CFOSAT散射计在轨工作状态良好,实际性能与设计预期一致,风速测量精度优于1.5 m·s-1,风向测量精度优于15°,空间分辨率可达12.5 km,在近岸风场监测、土壤湿度遥感和海冰面积估计等应用领域具有独特的优势.

The first rotating fanbeam scatterometer onboard China-France Oceanography Satellite(CFOSAT)is able to observe Earth’s surface at different incidence and azimuth angles using innovative observing geometry,and in turn to improve the retrieval of sea surface wind,soil moisture,sea ice extent,etc.After the CFOSAT was launched in October 2018,the performances of the CFOSAT Scatterometer(CSCAT)are being tested in orbit.This paper provides an overview of the CSCAT system,and then summarizes the key parameters of CSCAT tested in orbit,including calibration signal analyses,system noise analyses,and radar backscatter processing results analyses.Consequently,the first wind retrieval results of CSCAT are analyzed to assess the system performance.The wind speed accuracy of CSCAT is better than 1.5 m·s-1,and the wind direction accuracy is better than15°.The special resolution is better than 12.5 km.All these results show that CSCAT generally works well in orbit and has a unique advantage in the monitoring of nearshore winds,soil moisture,and sea ice extent.