TRMM and Other Sources Rainfall Product (TRMM Product 3B43)
Entry ID:
GES_DISC_TRMM_3B43_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 3B43 algorithm is to produce the best-estimate precipitation rate (in mm/hr) and root-mean-square (RMS) precipitation-error estimates from TRMM and other data sources. 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), microwave-adjusted merged geo-infrared (IR), and monthly accumulated Global Precipitation Climatology Centre (GPCC) rain gauge analysis. 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 gauge analysis using inverse-error-variance weighting to form the best-estimate precipitation rate and RMS precipitation-error estimates. These gridded estimates have a calendar month 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 5 MB.
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
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Description:
Data access URL for TRMM product 3B43
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Multimedia Sample
View full image
Caption:
3B43 TRMM and others combined surface rainfall, 2005/10/01-2005/11/01
Description:
Sample image of the TRMM 3B43 and others combined surface rainfall
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Geographic Coverage
(Click for Interactive Map)
Spatial coordinates
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N: 50.0
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S: -50.0
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E: 180.0
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W: -180.0
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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:
Monthly
Temporal Resolution Range:
Monthly - < Annual
Quality
Satellite/gauge relative error estimates are provided for each 0.25 x 0.25 degree box. The estimates are derived in two steps: (1) the error estimates of each input data are computed separately, mostly reflecting the sampling-induced uncertainty of each field and (2) a linear combination of these field errors is computed, in which each field error estimate is weighted by the inverse of its error-variance. There are currently no known deficiencies in the 3B43 algorithm. The quality of the 3B43 product is highly sensitive to the quality of the input data: TRMM adjusted merged-IR (product 3B42) and monthly accumulated TMI/TRMM Combined Instrument (TCI, product 2A12/3B31). If the quality of the input data is less than anticipated, then the quality of 3B43 will also be less.
Access Constraints
None
Data Set Progress
IN WORK
Distribution
Distribution Media:
FTP
Distribution Size:
increasing daily
Distribution Format:
HDF
Fees:
none
Personnel
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
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
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
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, P. Arkin, A. Chang, R. Ferraro, A. Gruber, J. Janowiak, A. McNab, B. Rudolph, and U. Schneider, 1997: "The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset," Bul. Amer. Meteor. Soc., 78, 5-20.
Huffman, G.J., R.F. Adler, B. Rudolph, U. Schneider, and P. Keehn, 1995: "Global Precipitation Estimates Based on a Technique for Combining Satellite-Based Estimates, Rain Gauge Analysis, and NWP Model Precipitation Information," J. Clim., 8, 1284-1295.
Extended Metadata Properties
(Click to view more)
Creation and Review Dates
DIF Creation Date:
2011-07-19
Last DIF Revision Date:
2013-05-14
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