Comprehensive evaluation of global precipitation products and their accuracy in drought detection in mainland China

Thorough evaluations of satellite precipitation products are necessary for accurately detecting meteorological drought. A comprehensive assessment of 15 state-of-the-art precipitation products (i.e., IMERG_cal, IMERG_uncal, GSMaP-G, CPC-Global, TRMM3B42, CMORPH-CRT, PERSIANN-CDR, PERSIANN, PERSIANN-CCS, SM2RAIN, CHIRPS, ERA5, ERA-interim, MERRA2, and GLDAS) is herein conducted for the period 2010 to 2019 giving special attention to their performance in detecting meteorological drought over mainland China at 0.25° spatial resolution. The cited precipitation products are compared against China’s gridded gauge-based Daily Precipitation Analysis (CGDPA) product, derived from 2400 meteorological stations, and their quality is assessed at daily, seasonal, and annual precipitation timescales. Meteorological droughts in the datasets are determined by calculating the Standardized Precipitation Evapotranspiration Index (SPEI). The performance of the precipitation products for drought detection with respect to the SPEI is assessed at three timescales (1-, 3-, and 12-month). The results show that the GSMaP-G outperforms other satellite-based datasets in drought detection and precipitation estimation. The MERRA2 and the ERA5 are on average closer to the CGDPA reference data than other reanalysis products for precipitation estimation and drought detection. These products capture well the spatial and temporal pattern of the SPEI in southern and eastern China having a probability of detection (PODs) above 0.6 and a correlation coefficient (CC) above 0.65. CPC-Global, IMERG satellite, and the ERA5 reanalysis product are ideal candidates for application in western China, especially in the Qinghai-Tibetan plateau and the Xinjiang Province. Generally, the accuracy of precipitation products for drought detection is improved with longer timescales of the SPEI (i.e., SPEI-12). This study contributes to drought-hazard detection and hydrometeorological applications of satellite precipitation products.