Performance Assessment of CRA40 and ERA5 Precipitation Products over China

Precipitation datasets derived from reanalysis products play a critical role in weather forecasting and hydrological applications. This study aims to assess the performance of two distinct reanalysis precipitation products, i.e., the first-generation Chinese global land-surface reanalysis precipitation product (CRA40) and the fifth-generation European reanalysis precipitation product (ERA5), over mainland China. The assessment is conducted with daily-scale gridded-point rain gauge data obtained from Chinese surface meteorological stations as reference, and the continuous and categorical statistical indicators as assessment metrics. The findings of this study are as follows: 1) CRA40 outperforms ERA5 in terms of the 13-year daily mean precipitation and seasonal daily precipitation. CRA40 shows better correlation coefficients (0.97), relative biases (5.25%), root mean square errors (0.34 mm), and fractional standard errors (0.05). 2) Both CRA40 and ERA5 generally exhibit an overestimation of precipitation over mainland China. The degree of overestimation is particularly pronounced in dry climatic regions (e.g., Xizang-Qinghai plateau, Xinjiang province), while wet regions (e.g., the middle and lower reaches of Changjiang River, and South China) demonstrate relatively less overestimation. 3) ERA5 shows better performance in the detection of daily precipitation than CRA40. Neither CRA40 nor ERA5 can well capture heavy precipitation events. These findings are expected to advance our understanding of the strengths and limitations of the reanalysis precipitation products, CRA40 and ERA5, over China.