GPS探测与FY-2反演大气可降水量对比分析

为深入了解FY-2卫星大气可降水量(PW)的反演质量,文章选取2012和2015年地基GPS水汽观测数据,与FY-2的PW反演产品进行了对比分析。结果表明:(1)北京、武汉和海口三站GPS/PW(PW_(GPS))与FY-2/PW(PW_(FY-2))在夏季存在显著正相关,三站的相关系数都达到0.67以上,夏季PW的均方根误差值、月平均偏差绝对值均小于冬季。北京与武汉站PW平均偏差和均方根误差在四季均具有明显日变化特征;(2)当PW_(GPS)20 mm时,北京、武汉、海口和拉萨站FY-2/PW与GPS/PW比较一致,PW偏差均值的绝对值和均方根误差较小,当PW_(GPS)20 mm时,PW偏差均值绝对值和均方根误差随PW_(GPS)值减小而迅速变大。FY-2的PW产品在夏季可以为大部分区域提供高时空分辨率、高精度的大气可降水量,在大气湿度非常低、冬季和夜间条件,反演结果精度有待提高。

Comparison of Precipitable Water Retrieved by FY-2 Satellite and GPS Observations

In order to better understand the quality of precipitable water retrieved from FY 2 satellite data (FY 2/PW), the comparison research is done in this study between the FY 2/PW and GPS/PW collected in 2012 and 2015. The results indicate that: (1) the two datasets are highly correlated at three stations (Beijing,Wuhan and Haikou) with correlation coefficients more than 0.67 in summer. The values of PW RMSE and monthly mean bias are less in summer than in winter. The bias and RMSE of PW for four seasons exhibited a pronounced diurnal variation in Beijing and Wuhan. (2) When the value of GPS/PW is greater than 20 mm, FY 2/PW agrees well with GPS/PW at Beijing, Wuhan, Haikou and Lhasa Stations. On the other hand, when the value of GPS/PW is less than 20 mm, the absolute values of PW bias and RMSE quickly increase with the decrease of GPS/PW. All the results show that the accuracy of FY 2/PW tends to be high in summer, but the retrieval results need some improvement in the conditons of low atmospheric humidity, winter and night.