ERA-5降水数据在澜沧江流域高山峡谷地区的适用性研究

以澜沧江流域典型高山峡谷地区为例,首先对最新发布的ERA-5再分析降水产品进行不同时空尺度下的精度评估,发现ERA-5数据与站点数据之间的相关性较高,可较好反映流域降水分布空间变化趋势,但高估了实测降水,存在着较大的系统误差,且误差有明显的时空变异特性,需经校正才可投入实际应用;然后使用比率偏差校正法对ERA-5进行校正,针对每个包含气象站的ERA-5网格计算其日降水事件对应的校正系数,将校正系数插值到每个网格,从而实现整个研究区域的校正,校正后的ERA-5数据在降水空间分布和数值上的精度均大幅度提升;最后采用水文模型间接评估校正效果,结果表明校正后的ERA-5降水径流模拟精度同样明显高于原始数据。

Research on Applicability of ERA-5 Precipitation Data in Alpine and Gorge Region of Lancangjiang River Basin

Taking the typical high mountain and gorge region of Lancangjiang River Basin as the research area,the accuracy of the latest ERA-5 reanalysis precipitation product was evaluated under different spatial and temporal scales.The results show that the consistency between ERA-5 data and observation data is high,and it can reflect the spatial variation trend of precipitation distribution in the basin.However,the precipitation is greatly overestimated in some areas,and there is a large systematic error,and the error has obvious spatiotemporal variation characteristics,so it can be put into practical application only after correction.In the process of using ratio bias correction method to correct ERA-5,the correction coefficient corresponding to daily rainfall events is calculated for each ERA-5 grid containing meteorological stations,and then the correction coefficients are interpolated into each grid to realize the correction of the whole study area.The accuracy of the corrected ERA-5 data in spatial distribution and numerical value of precipitation is greatly improved.Finally,hydrological model is used to indirectly evaluate the correction effect.The results show that the accuracy of runoff simulation after correction is significantly higher than before.