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

Details

• Journal Title:
  Journal of Hydrometeorology
• Personal Author:
  Watters, Daniel C. ; Gatlin, Patrick N. ; Bolvin, David T. ; Huffman, George J. ; Joyce, Robert ; Kirstetter, Pierre ; Nelkin, Eric J. ; Ringerud, Sarah ; Tan, Jackson ; Wang, Jianxin ; Wolff, David
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; NSSL (National Severe Storms Laboratory)
• Description:
  NASA’s multisatellite precipitation product from the Global Precipitation Measurement (GPM) mission, the Integrated Multi-satellitE Retrievals for GPM (IMERG) product, is validated over tropical and high-latitude oceans from June 2014 to August 2021. This oceanic study uses the GPM Validation Network’s island-based radars to assess IMERG when the GPM Core Observatory’s Microwave Imager (GMI) observes precipitation at these sites (i.e., IMERG-GMI). Error tracing from the Level 3 (gridded) IMERG V06B product back through to the input Level 2 (satellite footprint) Goddard Profiling Algorithm GMI V05 climate (GPROF-CLIM) product quantifies the errors separately associated with each step in the gridding and calibration of the estimates from GPROF-CLIM to IMERG-GMI. Mean relative bias results indicate that IMERG-GMI V06B overestimates Alaskan high-latitude oceanic precipitation by +147% and tropical oceanic precipitation by +12% with respect to surface radars. GPROF-CLIM V05 overestimates Alaskan oceanic precipitation by +15%, showing that the IMERG algorithm’s calibration adjustments to the input GPROF-CLIM precipitation estimates increase the mean relative bias in this region. In contrast, IMERG adjustments are minimal over tropical waters with GPROF-CLIM overestimating oceanic precipitation by +14%. This study discovered that the IMERG V06B gridding process incorrectly geolocated GPROF-CLIM V05 precipitation estimates by 0.1° eastward in the latitude band 75°N–75°S, which has been rectified in the IMERG V07 algorithm. Correcting for the geolocation error in IMERG-GMI V06B improved oceanic statistics, with improvements greater in tropical waters than Alaskan waters. This error tracing approach enables a high-precision diagnosis of how different IMERG algorithm steps contribute to and mitigate errors, demonstrating the importance of collaboration between evaluation studies and algorithm developers.
• Source:
  Journal of Hydrometeorology, 25(1), 125-142
• DOI:
  https://doi.org/10.1175/jhm-d-23-0134.1
• ISSN:
  1525-755X ; 1525-7541
• Format:
  PDF
• Publisher:
  American Meteorological Society
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Library
• Main Document Checksum:
  urn:sha-512:5e5487c325225a2e4b559f8af684fa693ed2a4920c81bab19fcacaf77fe0d6c372ec87f50fb261261aec4873ea31f7aaba5b4626f1700918d47121a64f263637
• Download URL:
  https://repository.library.noaa.gov/view/noaa/65010/noaa_65010_DS1.pdf
• File Type:
  [PDF - 7.58 MB ]