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TRMM 3-Hourly 0.25 deg. TRMM and Other-GPI Calibration Rainfall 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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Description: OPeNDAP Earth Science Data TRMM 3B42.

Multimedia Sample

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Caption: 3B42 TRMM and others combined 3 hour accumulated surface rainfall

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

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 Other-GPI Calibration Rainfall Data

Version: 7

Online Resource: http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?t...

Temporal Coverage

Start Date: 1997-12-31

Location Keywords

GEOGRAPHIC REGION > GLOBAL

Data Resolution

Latitude Resolution: 0.25 degree
Longitude Resolution: 0.25 degree
Horizontal Resolution Range: 10 km - < 50 km or approximately .09 degree - < .5 degree
Vertical Resolution: Surface
Temporal Resolution: 3-hourly
Temporal Resolution Range: Hourly - < Daily

Science Keywords

ATMOSPHERE > PRECIPITATION > PRECIPITATION RATE

ISO Topic Category

CLIMATOLOGY/METEOROLOGY/ATMOSPHERE

Platform

TRMM > Tropical Rainfall Measuring Mission

Instrument

PR > TRMM Precipitation Radar

TMI > TRMM Microwave Imager

VIRS > TRMM Visible Infrared Scanner

Project

EOS > Earth Observing System

EOSDIS > Earth Observing System Data Information System

Quality Adjusted GPI relative error estimates are provided for each 0.25 x 0.25 degree box. There are currently no known deficiencies in the 3B42 algorithm. The quality of the 3B42 product is highly sensitive to the quality of the input data: TRMM VIRS (product 1B01), TMI (product 2A12), and TRMM Combined Instrument (TCI) (product 3B31). If the quality of the input data is less than anticipated, then the quality of 3B42 will also be less.

Access Constraints None

Ancillary 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

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: 2250 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: Maryland

Postal Code: 20771

Country: USA

HYDROLOGY DATA SUPPORT TEAM

Role: TECHNICAL CONTACT

Phone: (301) 614-5165

Fax: (301) 614-5268

Email: gsfc-help-disc at lists.nasa.gov

Contact Address:

Hydrology Data Support Team, Code 610.2

Goddard Space Flight Center

City: Greenbelt

Province or State: MD

Postal Code: 20771

Country: USA

HYDROLOGY DATA SUPPORT TEAM

Role: DIF AUTHOR

Phone: (301) 614-5165

Fax: (301) 614-5268

Email: gsfc-help-disc at lists.nasa.gov

Contact Address:

Hydrology Data Support Team, Code 610.2

Goddard Space Flight Center

City: Greenbelt

Province or State: MD

Postal Code: 20771

Country: USA

Creation and Review Dates

Last DIF Revision Date: 2005-03-08

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