中国典型降水产品精度多时间尺度变化及空间分布

Precision variation of typical precipitation products at multi-time scale and their spatial distributions in China

为评估中国大陆区域典型长序列、高时间分辨率降水产品(MSWEP,TRMM,CMFD)在不同尺度的精度水平、演变特征和空间差异,基于2117个气象站近5 a的逐小时数据,选取相关系数(Corr)、均方根误差(RMSE)、相对误差中位数(REM)和击中率(POD)4个指标,系统地评估了降水产品在小时、日、旬、月尺度的精度及空间分布特征,建立了相关指标随时间尺度增加而演变的函数模型。结果表明:3组降水产品精度的空间分布总体表现为由西北逐渐向东南区域增加的特征,且POD和REM在各尺度均为MSWEP明显优于CMFD和TRMM,但Corr、RMSE在亚日和旬月尺度精度表现不一致;多尺度变化方面,RMSE和REM呈幂函数变化,而Corr和POD服从修正后的对数Gamma分布函数。研究成果可为降水产品的优选识别、精度提升和深度融合提供依据。

To evaluate the accuracy of 3 typical precipitation products,including MSWEP V2.8,TRMM 3B42 V7,and China Meteorological Forcing Dataset(CMFD),with long time series and high temporal resolution in China′s mainland,we analyzed them from the perspectives of multi-scale,evolution function and spatial heterogeneities.Based on the hourly data of 2117 meteorological stations in recent 5 a,the 4 indexes of correlation coefficient(Corr),root mean square error(RMSE),median of relative error(REM),and probability of detection(POD)were selected to systematically evaluate their accuracy and spatial distribution characteristics at the hourly,daily,ten-day and monthly scales,and the evolution function models were established to describe the trends of these indices accompanied with the increase of temporal scale.The results reveals that the accuracies of the 3 precipitation products,generally,increase from the northwest to the southeast regions,and MSWEP exhibits a higher accuracy than CMFD and TRMM in POD and REM at all scales while they show inconsistency in Corr and RMSE at sub-daily and ten-day/monthly scales.As for the evolution function models,RMSE and REM can be described by a power function,and Corr and POD from hourly to monthly scale follow a modified logarithmic Gamma distribution function well.The research results can provide references for optimal identification,accuracy improvement,and deep fusion of precipitation production.