伊犁河上游流域三种日尺度降水产品性能评估

Performance evaluation of three daily precipitation products in the upper reaches of the Ili River

伊犁河上游喇叭口地形条件导致其降水空间分布极不均匀,有限的地面观测站点难以真实反映日降水时空变化,因此,有必要评估不同降水产品在伊犁河上游的适用性。选用7种统计指标与广义三角帽法分别对三种降水产品(GPM、ERA5、CHIRPS)在伊犁河上游地区的精度与不确定性进行评估。结果表明:(1)ERA5的相关性、探测率、错报率最高,其估计的中雨与大雨降水量最准确;GPM的均方根误差最小,探测率、错报率最低;CHIRPS的相对偏差与平均误差最小,其探测率、错报率均介于GPM与ERA5之间,其估计的小雨降水量最准确;三种降水产品估计的暴雨降水量精度均不高,但ERA5要好于GPM与CHIRPS。(2)ERA5的日降水量不确定性介于GPM与CHIRPS之间,信噪比最大;GPM的日降水量不确定性最小,信噪比介于ERA5与CHIRPS之间;CHIRPS的日降水量不确定性最大,信噪比最小。(3)ERA5的日降水质量好于GPM与CHIRPS,可用于伊犁河上游地区降水特征分析;GPM的日降水量不确定性最小,通过系统校正提升其质量的可能性最大。研究成果可为伊犁河上游流域水文模拟与水资源变化分析提供支撑。

The topographic conditions of the bell in the upper reaches of the Ili River lead to an extremely uneven spatial distribution of precipitation,and it is difficult for limited observation stations to truly determine the spatial and temporal changes in daily precipitation.Therefore,it is necessary to assess the applicability of different precipitation products in the upper reaches of the Ili River.On the basis of seven statistical indicators and the generalized three-cornered hat method,we determined the accuracy and uncertainty of three precipitation products(GPM,ERA5,and CHIRPS) in the upper reaches of the Ili River.The results show that(1) ERA5 showed the highest correlation between POD and FAR,and its moderate and heavy rain precipitation estimates were the most accurate.The root mean square error of GPM was the smallest,and POD and FAR were the lowest.CHIRPS showed the smallest relative bias and mean error,its POD and FAR values were between those of GPM and ERA5,and its light rain precipitation estimates were the most accurate.The accuracy of rainstorm precipitation estimated by the three precipitation products was not high,but ERA5 was better than GPM and CHIRPS.(2) The uncertainty of daily precipitation of ERA5 was between that of GPM and CHIRPS,and the signal-to-noise ratio was the largest.GPM showed the lowest uncertainty of daily precipitation,and the signal-to-noise ratio was between that of ERA5 and CHIRPS.CHIRPS had the largest uncertainty of daily precipitation and the smallest signal-to-noise ratio.(3) The daily precipitation quality of ERA5 was better than that of GPM and CHIRPS,and it can be used to analyze the precipitation characteristics in the upper reaches of the Ili River.GPM had the lowest uncertainty of daily precipitation and is most likely to improve its quality through system calibration.The present findings provide support for hydrological simulation and water resource change analysis in the upper reaches of the Ili River.