The algorithm for the Integrated Multi-satellitE Retrievals for GPM (IMERG) has now been upgraded to Version 07. IMERG V07 involves a wide range of changes to all aspects of the algorithm, many of which are implemented in response to feedback on V06, which was the first time the IMERG record spanned the TRMM-GPM eras. IMERG V07 will be reprocessed for the entire TRMM-GPM record and thus supersedes all prior IMERG versions, as well as superseding the prior TRMM-based TMPA products (3B42, 3B43).

Retrospective Processing for the Final Run began on 1 July 2023. When this completes for the entire TRMM- GPM record, climatological calibrations will be computed for the Early and Late Runs, and both Initial Processing and Retrospective Processing for the Early and Late Runs will begin. This is expected to occur in Fall 2023. Links to the IMERG files are listed on the Data Directory of the GPM website: https://gpm.nasa.gov/data/directory, which point to archives hosted at the Goddard Earth Sciences Data and Information Services Center (GES DISC) https://disc.gsfc.nasa.gov/datasets?keywords=gpm%20imerg%2007 and the Precipitation Processing System (PPS) https://arthurhou.pps.eosdis.nasa.gov/Documents/Master_List_of_PPS_Data…, as well as several interactive sites. Please visit https://gpm.nasa.gov/data/news for the latest updates.

Initial evaluation results suggest that the changes in V07 collectively improve the performance of IMERG estimates, both in terms of its precipitation detection, systematic bias, and random bias. This includes improvements in IMERG over frozen, orographic, and coastal surfaces; in the consistency of histograms (including extreme values) between the TRMM and GPM eras; and performance over regions lacking gauge data, particularly the oceans. See Appendix 2: Initial Evaluation of IMERG V07. The next two sections summarize changes in IMERG for V07 and then list some known issues.