中法海洋卫星微波散射计后向散射测量误差分析  

Analysis of backscattering measurement error of CSCAT

作　　者：于淼淼 朱迪 董晓龙 林文明 马剑英 郎姝燕[4,5] YU Miaomiao;ZHU Di;DONG Xiaolong;LIN Wenming;MA Jianying;LANG Shuyan(Key Laboratory of Microwave Remote Sensing,National Space Science Center,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100190,China;School of Marine Sciences,Nanjing University of Information Science&Technology,Nanjing 210044,China;National Satellite Ocean Application Service,Beijing 100081,China;Key Laboratory of Space Ocean Remote Sensing and Applications,Ministry of Natural Resources,Beijing 100081,China)

机构地区：[1]中国科学院国家空间科学中心微波遥感技术重点实验室,北京100190 [2]中国科学院大学,北京100190 [3]南京信息工程大学海洋科学学院,江苏南京210044 [4]国家卫星海洋应用中心,北京100081 [5]自然资源部空间海洋遥感与应用重点实验室,北京100081

出　　处：《海洋气象学报》2024年第4期46-53,共8页Journal of Marine Meteorology

基　　金：国家重点研发计划项目(2021YFC2803300,2021YFC2803305)。

摘　　要：中法海洋卫星(China-France Oceanography SATellite,CFOSAT)搭载的微波散射计(SCATterometer,简记为“CSCAT”)采用扇形波束旋转扫描系统,以提供不同入射角和方位角组合的平均后向散射系数,反演高质量海面风场信息。系统采用创新型系统设计及扫描方式,雷达后向散射系数测量仍存在一定误差,尤其在高入射角和低风速条件下,归一化标准差(K_(p))代表了测量误差随风速和入射角的关系。基于数值天气预报(numerical weather prediction,NWP)的海洋定标法(NWP Ocean Calibration,NOC)用于L1B—L2A数据的处理,有效提高测量精度。针对L1B数据中条带的K_(p)值分析表明,在40°左右入射角和中等风速条件下,测量的精度较高。L2A数据中的风矢量单元(wind vector cell,WVC)误差分析结果表明,在低风速情况下测量误差较为显著。此外,基于对重新定标的数据分析,得到对地球物理噪声的一致估计。结果显示,在排除极低风速测量不确定性的影响后,地球物理噪声占比为20%~30%。The CFOSAT(China-France Oceanography SATellite)SCATterometer(CSCAT)adopts a pioneering fan-beam rotary scanning system to provide averaged backscattering coefficient of different combinations of various incidence angles and azimuth angles,obtaining high-quality retrieval information of ocean surface wind field.Despite the innovative system design and scanning mode,certain inaccuracies remain in measuring backscattering coefficient,especially under large incidence angles and low wind speed conditions.Then the K_(p)value,representing the normalized standard deviation,reflects the variation of measurement error with wind speed conditions and incidence angles.The NWP(numerical weather prediction)Ocean Calibration(NOC)method is applied during the processing of L1B-L2A data to effectively improve the measurement accuracy.The K_(p)of slices in L1B data indicates that the accuracy is better in the condition of about 40°incidence angle and medium wind speed.The error analysis of wind vector cells(WVCs)in L2A data shows that the measurement error is relatively large at low wind speed.Additionally,a consistent estimate of geophysical noise is obtained through recalibration data,and the geophysical noise accounts for 20%-30%after excluding the very low wind speed measurement.

关 键 词：中法海洋卫星(CFOSAT)微波散射计(CSCAT) 海洋定标 测量误差 传递误差 地球物理噪声 

分 类 号：P714.2[天文地球—海洋科学] P412.27