Analysis and Evaluation of IMERG and TMPA Satellite Precipitation Products in the Three Gorges Region Basin

We used precipitation data from ground stations (GAUGE) and statistical analysis to evaluate the accuracy of Day-1 Integrated Multi-satelliteE Retrievals for GPM (IMERG) satellite precipitation product in the Three Gorges Region basin. Accuracy was compared with its predecessor TRMM Multi-satellite Precipitaiton Analysis (TMPA). Our results show that: (1) The daily precipitation captures of TMPA and IMERG were consistent in spatial distribution but there were differences from the measured precipitation GAUGE. (2) TMPA and IMERG were more accurate on a basin scale but their accuracies were also acceptable on the grid scale. The overall performance of IMERG was better than TMPA in the 2014 hydrological year, including the flood season and the dry season. IMERG is more sensitive to light precipitation than TMPA. The probability density function (PDF) of precipitation ( < 5 ) mm estimated by IMERG was often higher than that of GAUGE and it needs to be further optimized. (3) The spatial distribution of R and RMSE indicates that TMPA and IMERG had good performance in the basin but IMERG is slightly better than TMPA. From the spatial distribution of ME and BIAS, TMPA and IMERG were similar while ME and BIAS were generally less than 0 in the lower reaches of the basin, and larger than 0 in the upper reaches of the basin. (4) R fluctuated over time and the overall correlation during the flood season was higher than that in the dry season. RMSE and ME show periodic changes over time with the error in the flood season being greater than the error in the dry season.