RFE2.0遥感降水数据在新疆的适用性评价

Evaluation of applicability of satellite-based RFE2.0 rainfall data in Xinjiang

结合新疆的65个气象观测站日降水数据,采用连续验证统计方法、分类验证统计方法对RFE2.0遥感降水数据在新疆的适用性进行了评估。结果表明:(1)通过连续验证统计分析,新疆地区平均偏差MBE(Mean Bias Error)总体对日降水量高估,均值为0.4 mm,在0.5 mm内的站点超过70%。RFE2.0遥感降水数据与地面观测站的日降水量之间相关系数R的平均值为0.4,表现为较低的相关性。从偏离真实值情况来说,东疆模拟值和观测值最接近。(2)分类验证统计方法对降水事件FBI(Frequency Bias Index)有所高估。按片区来说,降水事件高估的小值区主要在北疆,高估程度低于全疆平均水平。北疆的正确率POD(Probability of Detection)大于南疆、东疆,同时北疆发生空报率FAR(False Alarm Rate)的可能性也小于南疆、东疆。(3)通过实例验证了RFE2.0在北疆、南疆、东疆的可靠性。以上规律可为RFE2.0在新疆的应用提供科学依据。

With the daily precipitation data from 65 meteorological stations in Xinjiang, China, the verification methods including continuous statistics and classification statistics were used to evaluate the applicability of satellite- based RFE2.0 （ Rainfall estimation2.0） data. The results showed that RFE2.0 overestimated the daily precipitation in Xinjiang, with an average value of 0.4 mm MBE （mean bias error） ,more than 70% meteorological stations be- ing among 0.5 mm. The average value of correlation coefficient R between RFE2.0 and observation data was 0.4, indicating a low correlation with a descending order of the correlation value from north Xinjiang to east Xinjiang and then to south Xinjiang. The MAE（mean absolute error） was 0.23 -4.7 mm, with 1.16 mm average value. More than 50% meteorological stations with MAE were smaller than 1 mm. It was the northern, southern, eastern Xinjiang according to the order of relevance from big to small. The RMSE （ root mean square error） was 1.03 - 9.7 ram, with 3.32 mm average value. The descending order list was the north Xinjiang, south Xinjiang, east Xinjiang according to the MAE value. From the perspective of deviation from the real value, the simulated values in east Xinjiang was close to the observed value. There were 45 non-GTS stations selected to verify the possibility of precipitation events through classification statistics. FBI （frequency bias index） in Xinjiang was 0.82 - 3.71, the average value of FBI in northern,southern and eastern Xinjiang were 1.42,2.1,2.53. It was eastern,southern and northern Xinjiang ac- cording to size of FBI. In genenal, RFE2.0 overvalued possibility of rainfall events in Xinjiang, overestimation of precipitation events in northern Xinjiang is lower than the average of the whole Xinjiang. The POD value was 0.12 -0.95 ,with average value 0.67. The average value of POD was 0.74, 0.61, 0.61 ,respectively from north- ern,eastern and southern Xinjiang. POD in northern Xinjiang was higher than that of east and southern Xinjiang. The FAR was 0.18 -0.92 ,with 0.58 average value and 33% stations FAR less than 0.5. The average value of FAR in northern Xinjiang, eastern Xinjiang and southern Xinjiang was 0.43,0.74,0.69, respectively. The value of FAR in northern Xinjiang was smaller than eastern and southern Xinjiang. Two stations were selected to analyze respec- tively,Tuergate and Yuli observation stations from the southern Xinjiang, Caijiahu and Zhaosu observation stations from the northern Xinjiang,Shanshan and Yiwu observation stations from east Xinjiang, to verify the application of RFE2.0. The above rule can provide scientific basis for application of RFE2.0 in Xinjiang.