The Applicability Performance of the ERA5-Land Precipitation Datasets in Southwest China

Abstract

ERA5L precipitation reanalysis datasets were provided by the European Centre for Medium-Range Weather Forecasts（ECMWF） Fifth Generation Land Surface Reanalysis （ERA5L）. An investigation of the applicability of ERA5L precipitation reanalysis datasets produced for Sichuan， Chongqing， Guizhou， Yunnan and Xizang in Southwest China has been conducted.Statistical metrics， including Pearson correlation coefficients （CCs）， mean relative deviations （MREs）， root mean square errors （RMSEs）， probability of detections （PODs）， false alarm rates （FARs）， and critical success indices （CSIs）， were employed to assess the features and accuracy of ERA5L precipitation data using 441 national ground stations of the China Meteorological Administration between 2018 and 2020.The characteristics and deviations of ERA5L precipitation data were analysed in aspects of different regions， stations， altitudes， and timescales （monthly and seasonal） in our assessment phase.The following insights were revealed： （1） ERA5L better represents precipitation changes in the southwestern region； however， it tends to show higher precipitation levels than the in-situ observations， especially in Xizang.（2） In the Sichuan Basin， high correlation has been found between ERA5L precipitation data and in-situ observations， with a small error.The areas of Xizang， Yunnan， Guizhou and Western Sichuan are characterized by complex terrains and mountainous regions.The ERA5L data here has a relatively higher error.（3） The ERA5L exhibits a clear monthly variation in error， with a decline in overall precipitation leading to higher MRE， lower POD， and increased FAR from July to February.The MRE decreases， the POD increases， and the FAR rate decreases as precipitation increases from February to July.The quality of ERA5L varies between provinces and seasons.There is excellent precipitation quality in Chongqing during spring and autumn， and in Guizhou and Sichuan during summer and winter.（4） ERA5L precipitation is overestimated compared to in-situ observations in light rain magnitude， but underestimated in moderate and above-moderate rain.The underestimate becomes more severe as the rain intensity increases.As a whole， ERA5L has the potential for various applications in Southwest China.The hierarchy of ERA5L precipitation quality from high to low occurs in the following order： low altitude， medium altitude， and high altitude.In the context of five provinces， the order of applicability from high to low is as follows： Chongqing， Guizhou， Sichuan， Yunnan， and Xizang.

Keywords

• precipitation
• era5-land
• reanalysis data
• applicability assessment