Toward Reliable Satellite Precipitation for China: Assessing the New Generation of GPM Products

The Global Precipitation Measurement (GPM) mission's release of IMERG V07 in 2024 provides a novel data source for precipitation monitoring, yet its performance across complex terrains and diverse climatic regimes remains to be rigorously evaluated. This study presents a comprehensive assessment of IMERG V07's applicability across China and quantifies its improvements over the preceding V06 version. We developed an innovative multi-scale evaluation framework that integrates observations from 699 meteorological stations with the high-precision 0.25° CN05.1 gridded precipitation dataset, enabling systematic comparison between IMERG Late V07 and V06 at both station scale (2004-2020) and grid scale (2018-2020). Results reveal that V07 demonstrates significant improvements over V06 at the station scale, with an average increase of 0.05 in correlation coefficient and reductions of 6.96%, 4.18%, and 18.55% in RMSE, MAE, and PBIAS, respectively. Notably, V07 enhances detection capabilities for light precipitation (≤10mm/d) and heavy precipitation (≥50mm/d) by 4.65% and 11.58%, respectively. At the grid scale, V07 more accurately captures China's precipitation spatial patterns, particularly improving solid and trace precipitation identification in arid western regions (correlation coefficient increases of 0.1-0.2) and heavy precipitation event detection in eastern coastal areas (RMSE reductions exceeding 30%). Our findings demonstrate that IMERG V07 exhibits superior applicability across China's complex terrain and diverse climate zones, providing more reliable data support for hydrological modeling, drought monitoring, and flood forecasting applications. This study also establishes a methodological framework for evaluating satellite precipitation products in regions characterized by complex topography and climate diversity.