星载海洋遥感微波辐射计辐射测量受电离层及对流层大气环境的影响研究

Spaceborne microwave radiometer is an important instrument for remote sensing of ocean environmental parameters. Ocean radiation measurement for some channels is significantly affected by ionospheric Faraday rotation and tropospheric water vapor, cloud, rain and other atmosphere environmental parameters. This project examines the key issues of affecting the accuracy of sea surface brightness temperature observations, in order to improving the brightness temperature correction accuracy and expanding the range of applications of radiometer data. (1) In the study of the effect of ionosphere Faraday rotation, we comprehensively utilize three ionospheric electron density calculation methods to calculate Faraday rotation angle and analyze the mechanism of temporal and spatial variation. The corresponding brightness temperature errors are analyzed combined with the radiometer calibration accuracy. Two high precision Faraday rotation correction methods which are based on dual-band joint correction and altimeter ionosphere data correction are proposed. (2) In the study of the effect of troposphere, we simulate the tropospheric atmosphere transmittance and its radiation characteristics combined with the microwave radiative transfer model. Then,brightness temperature sensitivity for three kinds of typical atmosphere environmental parameters is analyzed and the influence on measurement accuracy of microwave radiometer under cloud and rain is determined.

星载海洋遥感微波辐射计是海洋环境要素遥感的重要仪器。电离层法拉第旋转效应和对流层水汽、云、雨等大气环境参数对辐射计部分通道的海面辐射测量影响显著。本项目研究影响辐射计海面亮温观测准确度的关键问题，为提高辐射计亮温数据校正精度，拓展其资料应用范围奠定基础。（1）在电离层法拉第旋转效应影响研究方面，综合利用三种电离层电子密度计算方法计算法拉第旋转角，分析法拉第旋转效应时空变化机理；结合辐射计定标精度，分析法拉第旋转造成的亮温误差；提出基于双频联合校正和高度计电离层反演产品校正的两种高精度法拉第旋转校正方法；（2）在对流层大气影响研究方面，结合微波辐射传输模型，仿真对流层大气透过性及辐射特性；针对三种典型大气环境参数进行亮温敏感性分析，确定云雨环境对微波辐射计观测精度的影响。

星载海洋遥感微波辐射计是海洋环境要素遥感的重要仪器。电离层法拉第旋转效应和对流层水汽、云、雨等大气环境参数对辐射计部分通道的海面辐射测量影响显著。本项目研究影响辐射计海面亮温观测准确度的关键问题，为提高辐射计亮温数据校正精度，拓展其资料应用范围奠定基础。（1）在电离层法拉第旋转效应影响研究方面，分析了法拉第旋转效应时空变化的机理，在构建沿观测路径快速计算法拉第旋转角的简化几何模型基础上，统计了法拉第旋转角随时空变化的规律，分析了电离层的垂直电子总含量、地球磁场矢量以及辐射计的扫描几何关系与法拉第旋转角变化的关系；结合辐射计定标精度，分析了法拉第旋转造成的观测亮温误差，给出了辐射计各通道亮温需法拉第旋转校正的阈值；综合比较了沿观测路径积分、薄层近似、极化模式三种法拉第旋转角计算方法，提出了基于L与X波段双频联合校正的高精度法拉第旋转校正方案。（2）在对流层大气影响研究方面，构建了降水情况下微波辐射传输模型，提出在大气透过率及上下行大气辐射中引入降水衰减系数，实现中等强度降雨下全极化微波辐射仿真；基于微波辐射传输仿真模型及微波辐射计实测亮温，针对大气水汽含量、云中液态水含量和降水强度三种典型大气环境参数进行亮温敏感性分析，分析了云雨环境对微波辐射计观测及环境参数反演的影响。