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Readme for TRMM Product 3B42 (V6)

Data Access for
TRMM and Other Satellites Precipitation Product

3B42: http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?tree=project&project=TRMM&dataGroup=Gridded&dataset=3B42:%203Hour%200.25%20x%200.25%20degree%20merged%20TRMM%20and%20other%20satellite%20estimates&version=006

Contents of TRMM and Other Satellites Precipitation Product 3B42

Summary

This document provides basic information on 3B42, TRMM and Other Satellites Precipitation Product.The TRMM Multi-Satellite Precipitation Analysis (TMPA; computed at fine intervals as 3B-42) intercalibrates (to 2B31) and combines 2A-12, SSMI, AMSR and AMSU precipitation estimates (referred to as HQ). IR estimates from geostationary IR observations are made by calibrating the IR brightness temperatures to the HQ estimates. The 3B-42 estimates consist of the HQ where available and IR otherwise, all scaled to match the monthly satellite/rain gauge analyses in 3B-43.The output is precipitation for 0.25x0.25 degree grid boxes on the latitude band 50 ° N-S every 3 hours. For more details of the algorithm, go to http://trmm.gsfc.nasa.gov/3b42.html

Data Flow Description

The data flow of 3B42 and the rest of the products are shown in Satellite Algorithm Flow Diagram.

Data Set Description

Data Characteristics

TRMM 3B42 Characteristics
Temporal Coverage Start Date: 1998-01-01; Stop Date: -
Geographic Coverage Latitude: 50°S - 50°N; Longitude:180°W - 180°E
Temporal Resolution 3-Hourly
Horizontal Resolution 0.25° x 0.25°; nlat = 400, nlon = 1440
Average File Size Compressed: ~285 KB; Original: ~4.5 MB
File Type HDF

Data Format Structure

Further information on the contents and structure of this product can be found in Volume 4 of the "File Specifications for PPS Products - Level 2 and Level 3."

Data Format Structure for 3B42
Name Type Record
Size
(byte)
Dim Size/
# of Records
Scaled
by
Range Unit Description
ECS Core Metadata Char Attribute 10,000  - - - - ECS Core Metadata
PS Metadata Char Attribute 10,000  - - - - Product Specific Metadata
Grid Structure Char Attribute 5,000  - - - - The specification of the grid geometry
Precipitation Float SDS nlat*nlon - 0.0 - 100  mm hr-1 TMPA precipitation estimate
Random Error Float SDS nlat*nlon - 0.0 - 200 mm hr-1 TMPA random error estimate
Note: nlat =  400: number of 0.25° latitude grids from 50°S - 50°N;
          nlon = 1440: number of 0.25° longitude grids from 180°W - 180°E;
          Missing data are given the value of -9999.
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Last updated: Dec 02, 2011 03:35 PM ET