星载全极化微波辐射计海面风向反演仿真研究

全极化微波辐射计是一种可以测量海面辐射全部4个Stokes参数的新型被动遥感仪器,是测量海面风场、尤其是海面风向的新手段。介绍了国际首台全极化微波辐射计WindSat的海面风向信号谐波特征,在分析风向反演180°模糊度现象的成因基础之上,提出了利用WindSat能够进行前-后向双视扫描的优势去除风向反演180°模糊度问题的思路;通过构建海面风场仿真场景,在WindSat模拟亮温数据中加入高斯白噪声后,使用最大似然估计法和中值滤波技术开展了海面风向反演。比较和分析了使用WindSat前向刈幅和WindSat前-后向刈幅观测数据的风向反演结果。结果表明:由于能够有效去除风向反演180°模糊度,使用前-后向刈幅观测数据的风向反演精度要明显优于仅仅使用前向刈幅的反演结果。

Simulation on Sea Surface Wind Direction Retrieval Using Spaceborne Fully Polarimetric Microwave Radiometer

The fully polarimetric microwave radiometer is a new passive remote sensing instrument,which can measure the whole of four Stokes parameters of sea surface radiation,that provides a new technique for sea surface wind vector,especially wind direction.First,the sea surface wind direction harmonics from WindSat,the first spaceborne fully polarimetric microwave radiometer,are introduced.In the basis of analysis of reason of wind direction inversion 180 degree ambiguity,the idea to solve this problem is proposed,which take advantage of two\|look capability of WindSat.Secondly,the sea surface wind field simulation scenarios are building,and the wind direction is retrieved by maximum likelihood estimation and median filter technique using the simulated WindSat brightness temperatures (Tbs) added gaussion white noise.Finally,the wind direction retrievals using between single\|look (only forward swath) and two\|look (forward and aft swath) Tbs data are compared.The analysis results show that retrievals using fore\|aft data are significantly higher accuracy,because it can effectively remove wind direction inversion 180 degree ambiguity.