静止卫星云图的云位置偏差及其几何校正

The Position Deviation of Geostationary Satellite Image and the Geometric Correction

利用静止气象卫星云图红外亮温数据和大气的温度层结曲线计算云顶高度。根据几何关系推导出观测云与真云位置偏差的计算公式,得到中国大陆地区对流云的观测偏差一般为5-20 km的结论。通过观测云经纬度和云顶高度计算真云经纬度,在此基础上进行了卫星云图几何校正实验,得到误差不超过2 km的云图校正结果。通过校正前后云图与雷达图的对比,验证了校正方法的有效性。最后,分析了云顶高度估算误差所造成的云图校正误差。

Cloud-top height is calculated by using the TBB of cloud image and the temperature protlle. The formula of observed deviation is derived according to the geometric relationship, and the conclusion is drawn that observed deviation is generally between 5 km and 20 km in China for the convective cloud with high cloud-top. The latitude and longitude of true cloud is calculated by using the latitude and longitude of observed cloud and cloud-top height. On this basis, a test of cloud image correcting is carried out, and the error of the test is less than 2 km. The validity of the correction method is verified by comparing the observed cloud image and corrected cloud image with radar image. Finally, the error caused by calculation error of the cloud-top height is analyzed.