Two-decades of GPM IMERG early and final run products intercomparison: Similarity and difference in climatology, rates, and extremes

Precipitation is an essential climate and forcing variable for modeling the global water cycle. Particularly, recent Integrated Multi-satellite Retrievals GPM (IMERG) product retrospectively provides unprecedented two decades of high-resolution satellite precipitation estimates. The primary goal this study to examine similarities differences between latest also arguably most popular, IMERG Early Final Run (ER FR) products across globe. results reveal that: (1) ER systematically estimates 12.0% higher annual rainfall than FR, particularly over land (16.7%); (2) FR show significant in instantaneous rates (Root Mean Squared Difference: RMSD = 2.38 mm h−1 normalized RMSD: RMSD_norm 1.09), especially Africa (RMSD 2.40 h−1) hot, arid regions (RMSD_norm 1.11), but less so Europe 2.16 cold areas 0.87); (3) measures 33.0% extreme exploration their a first-order assessment various hydrological utilities: designed be more suitable retrospective hydroclimatology resource applications, while earliest available product, though not bias-corrected by rain gauges, still shows potential utility operational rainfall-triggered hazards. findings can provide developers broader data users practitioners address inherent issues hardware limitations, retrieval algorithms, uncertainty quantification research applications.