Articles and Other

NASA information security management authorities mandated that continued use of the File Transfer Protocol (FTP) should not be allowed, even when used to provide access to publicly-available, non-sensitive information. This decision was made because FTP login credentials are sent in clear text. For this reason, they mandated that all FTP sites either convert to some form of encrypted login mechanism or be shut down.

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.

Version 7.04 Test TKIO 3.97.18

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. The GIS translation maintains the 0.1-degree spatial resolution of the original HDF5 data product. In July 2023, Version 7 IMERG was released in both HDF5 and GIS formats. In April 2019, Version 6 of IMERG had been released, covering June 2000 to 2019. The long- duration archive for all versions starting with Version 6 is a boon to scientific research and provides a training set for near real-time 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).