Oceanic Validation of IMERG-GMI Version 6 Precipitation Using the GPM Validation Network

• DOI: 10.1175/jhm-d-23-0134.1
• Publication Date: 2023-11-21T14:06:30Z
• Authors: Daniel C. Watters; Patrick N. Gatlin; David T. Bolvin; George J. Huffman; Robert Joyce; Pierre Kirstetter; Eric J. Nelkin; Sarah Ringerud; Jackson Tan; Jianxin Wang; David Wolff
• Keywords: Global Precipitation Measurement

Abstract NASA’s multisatellite precipitation product from the Global Precipitation Measurement (GPM) mission, Integrated Multi-satellitE Retrievals for GPM (IMERG) product, is validated over tropical and high-latitude oceans June 2014 to August 2021. This oceanic study uses Validation Network’s island-based radars assess IMERG when Core Observatory ’s Microwave Imager (GMI) observes at these sites (i.e., IMERG-GMI). Error tracing Level 3 (gridded) V06B back through input 2 (satellite footprint) Goddard Profiling Algorithm GMI V05 climate (GPROF-CLIM) quantifies errors separately associated with each step in gridding calibration of estimates GPROF-CLIM IMERG-GMI. Mean relative bias results indicate that IMERG-GMI overestimates Alaskan by +147% +12% respect surface radars. +15%, showing algorithm’s adjustments increase mean this region. In contrast, are minimal waters overestimating +14%. discovered process incorrectly geolocated 0.1° eastward latitude band 75°N–75°S, which has been rectified V07 algorithm. Correcting geolocation error improved statistics, improvements greater than waters. approach enables a high-precision diagnosis how different algorithm steps contribute mitigate errors, demonstrating importance collaboration between evaluation studies developers. Significance Statement Evaluation IMERG’s performance very limited date. Network conduct first extensive assessment its native resolution both oceans, traces product. (+12%) strongly (+147%) studied. assessed as should be optimal within due GMI’s status calibrator passive microwave constellation.