法拉第旋转对空间被动微波遥感的影响及消除

法拉第旋转是空间被动微波遥感重要的误差来源之一.本文研究了法拉第旋转变化的机理;分析了法拉第旋转对微波辐射计观测精度的影响;着重就1.4 GHz 正交极化通道亮温T_v以及10.7 GHz 相关极化通道亮温U的法拉第旋转校正展开讨论.通过仿真2006年海南某观测站点全年的星载微波辐射计观测数据并利用蒙特卡罗法模拟噪声的影响,分析比较了使用辅助数据(IRI 模型法)和极化模式(Yueh方法和Ribó方法)两种途径对法拉第旋转的校正效果,进而提出了一种应用IGS 关键词： 法拉第旋转 微波遥感 微波辐射计 国际GNSS服务网(IGS)

Eliminating the influence of Faraday rotation on passive microwave remote sensing from space

Faraday rotation (FR) is one of the important error sources for passive microwave remote sensing from space. In this paper, the principle of FR variation is studied. The influence of FR on accuracy for microwave radiometer measurement is analyzed. We concentrate on FR correction both at 1.4 GHz for the orthogonal channel brightness temperature T_v and at 10.7 GHz for the correlative channel brightness temperature U. By using the simulated observational data of spaceborne microwave radiometry at one point in Hainan province in 2006, we compare the effects of two approaches: correction by auxiliary data (IRI model correction) and correction by polarimetric mode (Yueh and Ribó methods). Noise generated by the Monte Carlo mode is included in the simulation. Then a new method of using TEC data released by international GNSS service (IGS) is proposed. For correction of T_v at 1.4 GHz, correction made by polarimetric mode is better than that by auxiliary data. Yueh method is best in effectiveness while IRI model method is worst. For the correction of U at 10.7 GHz, the correction by polarimetric mode is invalid, only correction by auxiliary data is valid. IGS data method greatly improves the correction accuracy and can replace the method of IRI model for nearly real time correction or final data correction.