Articles and Other

GPROF V05 is the rainfall algorithm used in TRMM V8. It matches in all ways the algorithm from the retrieval for GPM GMI and other satellites in the constellation. The Goddard Profiling Algorithm is a Bayesian approach that nominally uses the GPM Combined algorithm to create it's a-priori databases. Given the importance of these databases to the final product, they are worth reviewing before discussing particular changes to the algorithm. GPROF V03 was implemented at the launch of the GPM mission and thus had no databases from the GPM satellite itself.

This document describes the data file formats for all GPM products. Metadata is described in Metadata for GPM Products. The purpose of this file specification document is to define the file content and format for the GPM data products.The file specifications have been reviewed by the algorithm developers. Formats are
expected to change for each processing cycle.

This document contains a comprehensive list of all data products produced by the NASA Precipitation Processing System, including their Document Object Identifiers (DOIs)

This document describes the file naming conventions that will be used to name data products produced by the Precipitation Processing System (PPS) for the Global Precipitation Measurement (GPM) Mission. These file naming conventions are also intended to apply to files produced or reprocessed from the Tropical Rainfall Measuring Mission (TRMM) satellite during the period of GPM operations.

The purpose of this file specification document is to define the file content and format for the TRMM data products.

The algorithm for the Integrated Multi-satellitE Retrievals for GPM (IMERG) has now been upgraded to Version 06. The transition to V05 for the IMERG Final Run began 13 March 2019 at PPS and the new data started flowing down to the GES DISC as well. However, on 15 March 2019 an error was discovered in processing the initial batches of V06 IMERG Final Run months. A design choice in the code ended up retaining microwave precipitation estimates in the latitude band 60°N-S when there is snow/ice on the surface, rather than masking out the estimates due to low performance in such cases.

Users have requested a “simple” quality index (QI) to give some guidance on when they should most trust the Integrated Multi-satellitE Retrievals for GPM (IMERG). While the goal is reasonable, there is no agreement about how this quantity should be defined. After some discussion within the team, two distinctly different quality indices were chosen for the half-hourly and monthly data fields (QIh and QIm, respectively) for implementation in Version 05 and continued in V06.

NASA produces a GIS translation of IMERG for various accumulation periods that maintains the 0.1-degree resolution and global coverage of the original HDF5 data product. In April 2019, Version 6 of IMERG was released in both the HDF5 and the GIS formats. Version 6 is the first version to cover the approximately 20-year period from June 2000 to the present. This long-duration archive will be a boon to scientific research and will provide an expanded training set for realtime applications such as disaster monitoring.

1AGMI contains unpacked packet data from GMI science data from the GMI passive
microwave instrument flown on the GPM satellite. Swath S1 has 9 channels which are
similar to TRMM TMI (10V 10H 19V 19H 23V 37V 37H 89V 89H). Swath S2 has 4
channels similar to AMSU-B (166V 166H 183+/-3V 183+/-8V). Data for both swaths
is observed in the same revolution of the instrument. Swath S3 has ScienceDataHeader.
Swath S4 has full rotation for low freq channels (S1). Swath S5 has full rotation for high
freq channels (S2).

This document describes the basic idea of DPR data processing. It was originally written for the
algorithm used in the at-launch version (V03). The algorithm has been modied and improved
since then. Although the basic idea of data processing remains the same, the actual ow of
processing, in particular that in the solver module, has changed substantially. As a result, some
part of description in section 3.1 may not be relevant any more.

Changes in the DPR algorithm from V05 to V06