用IGS发布的TEC数据提高法拉第旋转校正精度

电磁波穿过电离层时引入的法拉第旋转是导致全极化微波辐射计观测亮温产生交叉极化的重要原因.分析得知IRI（international reference ionosphere）模型产生的TEC（total electron content）数据在部分低纬地区无法满足全极化辐射计对法拉第旋转的校正精度要求.为提高校正精度，分析了沿观测路径积分法和应用IGS（International GPS Service）发布的TEC数据校正两种方法对校正精度的影响.结果表明，沿观测路径积分法不能有效改善校正精度，而应用IGS数据校正可大幅提高低纬地区法拉第旋转校正精度，满足全极化微波辐射计对极化旋转角的校正精度要求.

IMPROVING THE CORRECTION ACCURACY OF FARADAY ROTATION BY USING TEC DATA RELEASED BY IGS

Faraday rotation induced when electromagnetic wave penetrates through ionosphere is the major source for the cross polarization in observed Stokes brightness temperature with a polarimetric microwave radiometer. Faraday rotation correction employing TEC (total electron content) data generated by IRI (international reference ionosphere) model can not meet polarization rotation correction accuracy in some low latitude regions. To improve the correction accuracy, the following two methods were used: 1.integrating Faraday rotation angle along observation path and 2.correcting Faraday rotation by using TEC data released by IGS. Analysis results show that the first method is hardly helpful to improve the correction accuracy, while the second one can improve Faraday rotation correction accuracy considerably. By using TEC data, the correction method can satisfy the correction accuracy of polarization rotation angles which a polarimetric microwave radiometer demands.