TRMM 3-Hourly 0.25 deg. TRMM and Others Rainfall Estimate Data
Entry ID: GES_DISC_TRMM_3B42_V7

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Summary
Abstract: The Tropical Rainfall Measuring Mission (TRMM) is a joint U.S.-Japan satellite mission to monitor tropical and subtropical precipitation and to estimate its associated latent heating. TRMM was successfully launched on November 27, at 4:27 PM (EST) from the Tanegashima Space Center in Japan.

The rainfall measuring instruments on the TRMM satellite include the Precipitation Radar (PR), an electronically scanning radar operating at 13.8 GHz; TRMM Microwave Image (TMI), a nine-channel passive microwave radiometer; and Visible and Infrared Scanner (VIRS), a five-channel visible/infrared radiometer.

The purpose of the 3B42 algorithm is to produce TRMM-adjusted merged-infrared (IR) precipitation rate (in mm/hr) and root-mean-square (RMS) precipitation-error estimates. The algorithm combines multiple independent precipitation estimates from the TMI, Advanced Microwave Scanning Radiometer for Earth Observing Systems (AMSR-E), Special Sensor Microwave Imager (SSMI), Special Sensor Microwave Imager/Sounder (SSMIS), Advanced Microwave Sounding Unit (AMSU), Microwave Humidity Sounder (MHS), and microwave-adjusted merged geo-infrared (IR). All input microwave data are intercalibrated to TRMM Combined Instrument (TCI) precipitation estimates (TRMM product 3B31); the iIR estimates are computed using monthly matched microwave-IR histogram matching; then missing data in individual 3-hourly merged-microwave fields are filled with the IR estimates. After the preprocessing is complete, the 3-hourly multi-satellite fields are summed for the month and combined with the monthly accumulated Global Precipitation Climatology Centre (GPCC) rain gauge analysis using inverse-error-variance weighting to form a monthly best-estimate precipitation rate, which is TRMM Product 3B43. The final step is to scale all the 3-hourly estimates for the month to sum to the monthly value (for each gridbox separately). The final 3B42 precipitation (in mm/hr) estimates have a 3-hourly temporal resolution and a 0.25-degree by 0.25-degree spatial resolution. Spatial coverage extends from 50 degrees south to 50 degrees north latitude.

The data are stored in the Hierarchical Data Format (HDF), which includes both core and product specific metadata. The file size is about 0.74 MB (compressed).

Important Changes: After the initial Version 7 processing, it was discovered that AMSU data were neglected in the first retrospective processing of both the Version 7 TMPA (3B42/43) and TMPA-RT (3B40/41/42RT) data series, which created an important shortcoming in the inventory of microwave precipitation estimates used during 2000-2010. In addition, a coding error in the TMPA-RT replaced the occasional missings in product 3B42RT with zeros. Accordingly, both product series were retrospectively processed again. The main impact in both series was to improve the fine-scale patterns of precipitation during 2000-2010 (and for 3B4xRT into late 2012). Averages over progressively larger time/space scales should be progressively less affected. [This is the reason the lack of AMSU went undiscovered; the merger system copes very reasonably with missing data.] Nonetheless, users are urged to switch to the newest Version 7 data sets. The newest runs may be identified by the file names: V.7 3B42/43 suffix of "7A.HDF" for January 2000 - September 2010 V.7 3B4xRT suffix of "7R2.bin" for 1 March 2000 - 6 November 2012 It continues to be the case that the Version 7 3B42/43 is some 4% higher than the calibrating data set (2B31) over oceans, which is still under study. However, the initial conclusion is that it results from the sampling mismatch between the (very sparse) TCI and the (much denser) microwave constellation. At the large scales this offset seems to be nearly a proportional constant.

TRMM Product FAQ: http://disc.sci.gsfc.nasa.gov/additional/faq/precipitation_faq.shtml

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Related URL
Link: GET DATA > OPENDAP DATA (DODS)
Description: OPeNDAP Earth Science Data 3B42 V7.


Link: GET DATA > MIRADOR
Description: Access to TRMM and Others Rainfall Estimate Product (3B42 V7)


Link: GET DATA > MIRADOR
Description: The Mirador Earth Science Data Search Tool that includes location and event gazetteers.


Link: GET DATA > SSW
Description: Area and parameter subsetting service.


Link: GET DATA > GIOVANNI
Description: This interface is designed for quick analyses of the TRMM Level-3 3-hourly rainfall product (3B42 V7). Users can plot area averages (area plot) and time series (time plot) for selected areas and time periods.


Link: GET RELATED SERVICE METADATA (SERF)
Description: This tool is online inter-comparison of 3-hourly TRMM (3B42 V6 and V7) and other global gridded precipitation products.


Link: VIEW RELATED INFORMATION
Description: Readme document for TRMM and Others Rainfall Estimate Product (3B42)


Link: VIEW RELATED INFORMATION
Description: Information and data access for all of the Goddard DAAC's hydrology data holdings, including TRMM data from the TMI, Precipitation Radar (PR) and Visible and Infrared Scanner (VIRS) instruments, the Ground Validation (GV) radar data, and ancillary and correlative data products.


Geographic Coverage
 N: 50.0 S: -50.0  E: 180.0  W: -180.0

Data Set Citation
Dataset Originator/Creator: Tropical Rainfall Measurement Mission Project (TRMM)
Dataset Title: TRMM 3-Hourly 0.25 deg. TRMM and Others Rainfall Estimate Data
Dataset Publisher: Goddard Space Flight Center Distributed Active Archive Center (GSFC DAAC)
Version: 7
Online Resource: http://disc.gsfc.nasa.gov/datacollection/GES_DISC_TRMM_3B42_V7.shtml


Temporal Coverage
Start Date: 1998-01-01


Location Keywords
GEOGRAPHIC REGION > GLOBAL


Data Resolution
Latitude Resolution: 0.25 degree
Longitude Resolution: 0.25 degree
Vertical Resolution: Surface
Temporal Resolution: 3-hourly


Science Keywords
ATMOSPHERE >PRECIPITATION >PRECIPITATION RATE    [Definition]


ISO Topic Category
CLIMATOLOGY/METEOROLOGY/ATMOSPHERE


Platform
TRMM >Tropical Rainfall Measuring Mission    [Information]


Instrument
PR >TRMM Precipitation Radar    [Information]
TMI >TRMM Microwave Imager    [Information]
VIRS >TRMM Visible Infrared Scanner    [Information]


Project
CWIC >CEOS WGISS Integrated Catalog    [Information]
EOS >Earth Observing System    [Information]
EOSDIS >Earth Observing System Data Information System    [Information]
ESIP >Earth Science Information Partners Program    [Information]
GPCP >Global Precipitation Climatology Project    [Information]
TRMM >Tropical Rainfall Measuring Mission Project    [Information]


Quality
Random error estimates (mislabeled “relative error” for historical reasons) are provided for each 0.25 x 0.25 degree box. The quality of the 3B42 product is highly sensitive to the quality of the input data: TMI (product 2A12), TRMM Combined Instrument (TCI; product 2B31), and the other input datasets listed in the Summary. If the quality of the input data is less than anticipated, then the quality of 3B42 will also be less. For more, see, ftp://meso-a.gsfc.nasa.gov/pub/trmmdocs/3B42_3B43_doc.pdf


Access Constraints
None


Keywords
EOSDIS


Data Set Progress
IN WORK


Originating Center
NASA GSFC GES DISC


Data Center
Goddard Earth Sciences Data and Information Services Center (formerly Goddard DAAC), Global Change Data Center, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA    [Information]
Data Center URL: http://disc.gsfc.nasa.gov/

Data Center Personnel
Name: GES DISC HELP DESK SUPPORT GROUP
Phone: 301-614-5224
Fax: 301-614-5268
Email: gsfc-help-disc at lists.nasa.gov
Contact Address:
Goddard Earth Sciences Data and Information Services Center
Code 610.2
NASA Goddard Space Flight Center
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA



Distribution
Distribution_Media: FTP
Distribution_Size: file size: 10949 kb
Distribution_Format: HDF
Fees: none


Personnel
GEORGE HUFFMAN
Role: INVESTIGATOR
Phone: 301-614-6308
Fax: 301-614-5492
Email: George.J.Huffman at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Mailstop 612
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA


GES DISC HELP DESK SUPPORT GROUP
Role: TECHNICAL CONTACT
Phone: 301-614-5224
Fax: 301-614-5268
Email: gsfc-help-disc at lists.nasa.gov
Contact Address:
Goddard Earth Sciences Data and Information Services Center
Code 610.2
NASA Goddard Space Flight Center
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA


ZHONG LIU
Role: DIF AUTHOR
Email: Zhong.Liu-1 at nasa.gov
Contact Address:
NASA
Goddard Space Flight Center
Mailstop 610.2
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA


Publications/References
Product Readme: ftp://meso-a.gsfc.nasa.gov/pub/trmmdocs/3B42_3B43_doc.pdf

File Specifications for TRMM Products: ftp://pps.gsfc.nasa.gov/pub/v7filespec/filespec.TRMM.V7.pdf

Metadata for TRMM Products: ftp://pps.gsfc.nasa.gov/pub/v7filespec/filespecMeta.TRMM.V7.pdf

TRMM V6 vs. V7 Major Data Format Changes: http://pps.gsfc.nasa.gov/Documents/formatChangesV7.pdf

Huffman, G.J., 1997: "Estimates of Root-Mean-Square Random Error for Finite Samples of Estimated Precipitation," J. Appl. Meteor., 1191-1201.

Huffman, G.J., R.F. Adler, D.T. Bolvin, G. Gu, E.J. Nelkin, K.P. Bowman, Y. Hong, E.F. Stocker, D.B. Wolff, 2007: The TRMM Multi-satellite Precipitation Analysis: Quasi- Global, Multi-Year, Combined-Sensor Precipitation Estimates at Fine Scale. J. Hydrometeor., 8(1), 38-55. PDF available at ftp://meso.gsfc.nasa.gov/agnes/huffman/papers/ TMPA_jhm_07.pdf.gz

Huffman, G.J., R.F. Adler, D.T. Bolvin, E.J. Nelkin, 2010: The TRMM Multi-satellite Precipitation Analysis (TMPA). Chapter 1 in Satellite Rainfall Applications for Surface Hydrology, F. Hossain and M. Gebremichael, Eds. Springer Verlag, ISBN: 978-90-481-2914-0, 3-22.

Creation and Review Dates
DIF Creation Date: 2011-07-19
Last DIF Revision Date: 2014-05-16

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