Evaluation of the {ERA}5 reanalysis precipitation dataset over Chinese Mainland

Reanalysis precipitation products are important datasets for precipitation estimates over ungauged areas. The objective of this study was to evaluate the accuracy of the newly released fifth-generation reanalysis product of the European Centre for Medium Range Weather Forecasts (ECMWF), i.e., ERA5, for precipitation estimates over Chinese Mainland during 2003-2015. In this study, we evaluated the ERA5 reanalysis data using gridded gauge precipitation. Both categorical and continuous verification scores were calculated. The results show that the detection capacity of ERA5 varies across the four sub-regions of Chinese Mainland. ERA5 tends to misdetect daily precipitation events in the south of the northwestern arid climate (NAC) and north of plateau climate (PC) zones. In addition, it is more difficult for ERA5 to accurately detect moderate or higher daily precipitation events (above 10 mm/day). Error analysis show that ERA5 product has higher root mean-square error (RMSE) values in the tropical and subtropical climate zone (TSC) with a relatively wet climate. Compared to satellite-based precipitation product, ERA5 has larger relative biases in precipitation estimates over Chinese Mainland and it tends to over- and underestimate light precipitation events and moderate and heavy precipitation events, respectively. Based on the analysis of the accuracy of ERA5 during typhoon-induced extreme precipitation, ERA5 can identify the precipitation distribution and center, but underestimates extreme precipitation. Overall, the results of this study provide references for the use of ERA5 in hydrological applications over Chinese Mainland.