This section outlines the primary sources for downloading GPM and TRMM precipitation data from archive sites at Goddard Space Flight Center, including basic instructions for using each source.
NOTE: Use of the PPS FTP and STORM requires you to first register your email address. Click here to register.
- FTP (PPS)
- Giovanni (GES DISC)
- FTP (GES DISC)
- GrADS Data Server (GDS)
- GPM Ground Validation Data Portal
PPS provides real-time processing and post-processing of the TRMM science data is performed by the TRMM Science Data and Information System (TSDIS). Working with the TRMM principal investigators and science algorithm developers, PPS maintains the operational science data processing system and ensures the timely processing of all TRMM science instrument data. During routine operations, raw instrument data is received in near real-time by PPS and then processed by the first tier of science algorithms to produce calibrated, swath-level instrument data. Using this calibrated, swath-level instrument data, the second tier of algorithms are used to compute geophysical parameters, such as precipitation rate, also at the swath-level resolution. At the final stage of processing, the third tier algorithms produce gridded geophysical parameters from the first- and second-tier instrument data. All TRMM products are archived and distributed by the Goddard Distributed Active Archive Center (GES DISC DAAC). For further information on PPS operations, please visit the PPS homepage.
Registering to Download Data (required)
In order to download data from the PPS FTPs you must first register your email address with the Precipitation Processing System, using this page: http://registration.pps.eosdis.nasa.gov/registration/
Once you submit this form you will receive an email requesting you to verify your email address. Click the link in this email to complete the registration process. You will then receive a second email confirming your registration.
You can now log in to any of the PPS FTP servers (outlined below) using your email address as the username and password.
NOTE: Although direct links to the FTP are included on these pages, it is recommended to use a dedicated FTP client to access the PPS FTP. Certain web browsers are also able to browse the FTP, but some users have experienced errors with this method.
The Precipitation Processing System hosts several FTP servers to access the different types of TRMM and GPM data:
- ftp://arthurhou.pps.eosdis.nasa.gov: New server for Production (PROD) TRMM and GPM data.
- ftp://jsimpson.pps.eosdis.nasa.gov: New server for Near-Realtime (NRT) TRMM and GPM data.
- ftp://trmmopen.pps.eosdis.nasa.gov: Old server for "Production" TRMM data. Does not contain GPM data, but may be maintained to preserve access to the popular 3B42RT algorithm.
File Naming Convention
In general, GPM data products are named using the following format:
[algorithm level].[satellite].[instrument].[algorithm name].[year / month / date].[data start time hr/min/sec UTC].[data end time UTC].[sequence indicator showing orbit # (L2) or day/month (L3)].[algorithm version].[data format]
This is a Level 2A product, using the GPM satellite's GMI sensor, using the "GPROF 2008" algorithm, showing data from Novemeber 1st 2013 starting at 23:51:52 UTC and ending at 01:24:00 UTC, orbit number 352, using version 03C of the algorithm, in HDF5 format.
For a more detailed explanation of GPM file naming conventions, please refer to the following document: File Naming Convention for Precipitation Products For the Global Precipitation Measurement (GPM) Mission
TRMM Production FTP Directory Structure
The /trmmdata directory serves two purposes. First, the trmmdata directory is the archive that the TRMM and GPM data ordering system called STORM uses to obtain TRMM data. The most user-friendly way to obtain TRMM data files may be to use STORM by going to https://storm-pps.gsfc.nasa.gov/storm/ . Second, the trmmdata directory is a place where researchers can download data files via an FTP client in their web browser or a stand-alone FTP client such as the "ftp" command in Linux. Only some of the subdirectories of trmmdata are likely to be useful to researchers looking at TRMM data with an FTP client rather than through STORM.
If you know which TRMM HDF4 data product you are interested in, you can obtain the granules of that data product in the ByDate subdirectory of trmmdata. Other specialized directories that may be of interest are the 3G subdirectory, which contains the 3G family of ASCII gridded products, and the GIS subdirectory, which contains the TMPA 3-hour gridded surface precipitation product converted into a GIS data-format (TIFF+WorldFile).
An alphabetical list of the subdirectories of trmmdata follow although not all of them are of interest to first time TRMM researchers.
- 3G: Contains the "3G" family of data products which contain ASCII text gridded TRMM data. Each file contains either 24 one-hour grids to summarize one day or contains one grid that summarizes an entire month. The file format described in the following documents available on ftp://trmmopen.pps.eosdis.nasa.gov/pub/ : README.3G68, README.3G01, README.3G68.QuarterDegree, and README.3G68Land .
- Auxiliary: Contains orbit-definition files not intended for use by typical TRMM researchers.
- Browse: Contains one PNG browse image for each HDF4 granule of many TRMM standard data products. Browse images are rarely downloaded directly from the FTP site and are instead viewed from a link in the Search Result table of the STORM data ordering system: https://storm-pps.gsfc.nasa.gov/storm/ .
- ByDate: Perhaps the most popular FTP directory for obtaining TRMM standard products. Organized by reprocessing data version, year, month, and day. The file format of these files are documented in the V7 file specification: http://pps.gsfc.nasa.gov/Documents/filespec.TRMM.V7.pdf .
- ByInstrument: An alternative FTP directory for obtaining TRMM standard products. Organized the same way as the ByDate subdirectory, except that an instrument-specific subdirectory occurs in between data version and year.
- CSI: This directory is no longer active. Prior to the launch of GPM, it contained subsets of TRMM standard products over pre-defined geographic regions.
- Climatology: Contains files in the TRMM Composite Climatology developed by Wang, Adler, Hoffman, and Bolvin. A journal article on this topic is available here: http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00331.1 .
- GIS: Contains a GIS-friendly reformatted version of the TMPA data product (aka TRMM 3B42). TMPA is a 3-hourly average global grid of surface rainfall estimates from a collection of microwave radiometers. The GIS-reformatted version is a 2-byte TIFF image plus an ESRI WorldFile text metadata file. This format is documented here: ftp://trmmopen.gsfc.nasa.gov/pub/trmmdata/GIS/README.GIS.pdf
- L0: This subdirectory contains low-level packet-data downloaded from the TRMM satellite. Typical TRMM researchers are unlikely to be interested in this data. Furthermore, this data is not written in HDF4, so it cannot be read by PPS tools such as the THOR data viewer.
- PF: The files of the TRMM Precipitation Feature database. These files are a useful way to summarize rain events observed by TRMM, although they are not designated as a TRMM standard product. Documentation of the TRMM Precipitation Feature database is available here: http://trmm.chpc.utah.edu/ .
- SpecialLH: Contains latent heating products of interest only to latent-heating researchers.
- shortTermAuxiliary, shortTermGV, and shortTermMOC: Does not contain files of interest to beginning TRMM researchers.
Science Team On-Line Request Module (TRMM Data Ordering) (STORM) provides an additional way to query, research, and download TRMM products. This site also provides related links to TRMM content, PPS activities, and additional product information.
Giovanni is a Web-based application developed by the Goddard Earth Sciences Data and Information Services Center (GES DISC) that provides a simple and intuitive way to visualize, analyze, and access vast amounts of Earth science remote sensing data without having to download the data (although data downloads are also supported). Giovanni is an acronym for the Geospatial Interactive Online Visualization ANd aNalysis Infrastructure.
OPeNDAP is a framework that simplifies all aspects of scientific data networking. OPeNDAP provides software which makes local data accessible to remote locations regardless of local storage format. OPeNDAP also provides tools for transforming existing applications into OPeNDAP clients (i.e., enabling them to remotely access OPeNDAP served data). OPeNDAP software is freely available.
The NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) is one of twelve NASA Science Mission Directorate (SMD) Data Centers that provide Earth science data, information, and services to research scientists, applications scientists, applications users, and students. The GES DISC is the home (archive) of NASA Precipitation and Hydrology, as well as Atmospheric Composition and Dynamics remote sensing data and information. The DISC also houses the Modern Era Retrospective-Analysis for Research and Applications (MERRA) data assimilation datasets (generated by GSFC’s Global Modeling and Assimilation Office), and the North American Land Data Assimilation System (NLDAS) and Global Land Data Assimilation System (GLDAS) data products (both generated by GSFC's Hydrological Sciences Branch).
The Grid Analysis and Display System (GrADS) is an interactive desktop tool that is used for easy access, manipulation, and visualization of earth science data. GrADS has two data models for handling gridded and station data. GrADS supports many data file formats, including binary (stream or sequential), GRIB (version 1 and 2), NetCDF, HDF (version 4 and 5), and BUFR (for station data). GrADS has been implemented worldwide on a variety of commonly used operating systems and is freely distributed over the Internet.
The goal of this site is to provide a one-stop-shopping portal for accessing the various radar, disdrometer, gauge and other instrument data sets supporting GPM GV activities. Use the tabs above to access the various datasets, including:
- Field Campaigns
- Validation Network
- Wallops Precipitation Research Facility