我国台风高发期东海和南海海区GIIRS/FY-4A温度反演廓线精度研究

A STUDY ON THE ACCURACY OF TEMPERATURE PROFILE RETRIEVED FROM GIIRS/FY-4A OVER THE EAST AND SOUTH CHINA SEA

基于欧洲中期天气预报中心再分析资料ERA5,对GIIRS/FY-4A温度反演廓线在我国台风高发期东海和南海海区的反演精度进行研究,结果表明:(1)东海海区,无云时GIIRS质量控制0的数据总体RMSE为1.71 K,150~450 hPa高度范围内RMSE小于1 K,450 hPa至近海面RMSE在2 K以内。质量控制1的数据反演精度低且随高度的增加误差增大;有云时,质量控制0和1的反演数据总体RMSE为4.72 K和5.55 K。(2)南海海区,无云时,质量控制0的数据总体RMSE为1.67 K,150~800 hPa范围内RMSE小于1 K,反演精度较东海海区略高。质量控制1的数据RMSE为5.07 K。有云时,质量控制0和1的数据RMSE为6.68 K和7.56 K。(3)随着台风“利奇马”等级加强直至最大等级(海上发展阶段),GIIRS可信度较高的反演数据量呈现下降趋势,反演台风周边热力结构存在诸多不确定性,需要借助其他资料进行验证。

Based on the reanalysis data ERA5 from the European Centre for Medium-Range Weather Forecasts,the accuracy of the temperature profile retrieved from GIIRS/FY-4A in the East China Sea and South China Sea in the high-incidence period of typhoon in China is studied.The results show that:(1)In the East China Sea under clear sky,the overall RMSE of GIIRS quality control 0 data is 1.71 K,the RMSE is less than 1 K for the range of 150—450 hPa and the RMSE from 450 hPa to the near sea surface is within 2 K;the data inversion accuracy of quality control 1 is low and the error increases with height.Under cloudy sky,the overall RMSE of the retrieved data for quality control 0 and 1 is 4.72 K and 5.55 K,respectively.(2)In the South China Sea under clear sky,the overall RMSE of quality control 0 data is 1.67 K,the RMSE is less than 1 K for the range of 150—800 hPa,and the inversion accuracy is higher than that in the East China Sea;the RMSE of quality control 1 data is 5.07 K.Under cloudy sky,the RMSE of the data for quality control 0 and 1 is 6.68 K and 7.56 K,respectively.(3)As the level of Typhoon Lekima is strengthened to the maximum level(offshore development stage),the amount of retrieved data with high GIIRS credibility shows a reducing trend.There are many uncertainties in the retrieval of the thermal structure around the typhoon and thus other information is needed for verification.