Applicability analysis of GPM IMERG satellite precipitation data in cloudy and foggy regions: a case study of Guizhou Province, China

Guizhou Province, a typical karst region in Southwest China characterized by complex terrain and a cloudy and foggy climate, holds significant importance for the high-precision monitoring of satellite precipitation data. Based on observational data from 84 meteorological stations in Guizhou Province from 2000 to 2020, this study systematically evaluates the applicability of GPM IMERG satellite precipitation data across annual, seasonal, monthly, and station-level scales using analysis metrics such as linear regression, correlation coefficients, and relative deviations. The results indicate that: (1) Overall, GPM IMERG data exhibit good agreement with ground station data at the annual scale, with an average relative error of -2.59%; (2) At the seasonal scale, variations exist among the four seasons, with the highest correlation in summer (R = 0.72) and poorer performance in winter, necessitating further considerations during application; (3) At the monthly scale, GPM IMERG data demonstrate significant linear correlations (R = 0.86); (4) Station-level monthly scale analysis reveals that the correlation coefficients of all stations exceed 0.80, though some variability exists among stations, with 64 stations showing relative deviations between -10% and 10%. These findings provide a scientific basis for optimizing the application of precipitation data and improving water resource management in the Guizhou region.