Personal tools
You are here: GES DISC Home Precipitation Documentation TRMM_README TRMM Monthly 0.5 x 0.5 Degree Combined Rainfall Data 3B31

TRMM Monthly 0.5 x 0.5 Degree Combined Rainfall Data 3B31

Data Access for

3B31: http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?tree=project&dataset=3B31%20%28Version%20007%29:%20Monthly%200.5%20x%200.5%20degree%20Combined%20Rainfall&project=TRMM&dataGroup=Gridded&version=007

 


Contents:

Summary

3B31, "Rainfall Combined", uses the high quality retrievals done for the narrow swath
in 2B31 to calibrate the wide swath retrievals generated in 2A12. For each 0.5 x 0.5 degree
latitude/longitude box and each vertical layer, an adjustment ratio will be calculated for
the swath overlap region for one month. Only TMI pixels with 2A12 pixelStatus equal to
zero are included in monthly averages. The major e ffect of the pixelStatus requirement
is to remove sea ice.

Data Flow Description

The data flow of all products are shown in Satellite Algorithm Flow Diagram.

3B31 V7 User's Guide

Data Set Description

Data Characteristics

Temporal Coverage Start Date: 1997-12-08; Stop Date: -
Geographic Coverage Latitude: 40°S - 40°N;Longitude:180°W - 180°E
Temporal Resolution Monthly
Horizontal Resolution 0.5° x 0.5°; nlat = 160, nlon = 720
Average File Size Compressed: ~37 MB
File Type HDF


Data Format Structure

The following table summarizes the contents and structure of the TRMM Monthly 0.5 x 0.5 Degree Combined Rainfall Data (3B31) product. Further information on the contents and structure of this product can be found in File Specifications for TRMM Products - Version 7.00

Data Format Structure for 3B31, TRMM Monthly 0.5 x 0.5 Degree Combined Rainfall Data
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
GridStructure Char Attribute 5,000  - - - - GridStructure gives the specification of the geometry of the grids.
surfacePrecipTMI Float SDS nlat*nlon - 0.0 ~ 3000.0 mm Surface rain from 2A12 accumulated in each 0.5° x 0.5° box
convectPrecipTMI Float SDS nlat*nlon - 0.0 ~ 3000.0 mm Convective surface rain from 2A12 accumulated in each 0.5° x 0.5° box
rainWaterTMI Float SDS nlat*nlon*nlayer - 0.0 ~ 10.0 g m-3 Monthly mean rain water content from 2A12 at each vertical layer in each 0.5° x 0.5° box
snowTMI

Float SDS

4 nlat*nlon*nlayer - 0.0 ~ 10.0 g m-3 Monthly mean snow liquid content from 2A12 at each vertical layer in each 0.5° x 0.5° box
graupelTMI Float SDS nlat*nlon*nlayer - 0.0 ~ 10.0 g m-3 Monthly mean graupel liquid content from 2A12 at each vertical layer in each 0.5° x 0.5° box
npixTotalTMI Integer SDS nlat*nlon - 1 ~ 10000 - The monthly number of pixels with pixelStatus equal to zero for each grid. The major eff ect of the pixelStatus requirement is to remove sea ice. npixTotalTMI is used to compute the monthly means described above.
surfacePrecipCOMB Float SDS nlat*nlon - 0.0 ~ 3000.0 mm Surface rain from 2B31 accumulated in each 0.5° x 0.5° box
rainWaterCOMB Float SDS nlat*nlon*nlayer - 0.0 ~ 10.0 g m-3 Rain water content at each vertical layer from 2B31 accumulated in each 0.5° x 0.5° box
snowCOMB Float SDS nlat*nlon*nlayer - 0.0 ~ 10.0 g m-3 Snow water content at each vertical layer from 2B31 accumulated in each 0.5° x 0.5° box
graupelCOMB Float SDS nlat*nlon*nlayer - 0.0 ~ 10.0 g m-3 Graupel water content at each vertical layer from 2B31 accumulated in each 0.5° x 0.5° box
npixTotalCOMB Integer SDS nlat*nlon - 1 ~ 10000 - The monthly number of pixels npixTotalCOMB is used to compute the monthly means
described above.
surfAdjRatio Float SDS nlat*nlon - - - The ratio of 2B31 to 2A12 surface rainfall, calculated from the swath overlap region for each 0.5° x 0.5° box
surfAdjRatiooverlap Float SDS nlat*nlon - - - The ratio of 2B31 to 2A12 surface rainfall, calculated from the swath overlap region for each 0.5° x 0.5° box

Parameters used in above table:
Name Value Definition
nlat 160 the number of 0.5° grid intervals of latitude from 40° N to 40° S
nlon 720 the number of 0.5° grid intervals of longitude from 180° W to 180° E
nlayer 28 the number of profiling layers


28 Vertical Layers
Layer Index Layer Top Height
1 0.5 km
2 1.0 km
3 1.5 km
4 2.0 km
5 2.5 km
6 3.0 km
7 3.5 km
8 4.0 km
9 4.5 km
10 5.0 km
11 5.5 km
12 6.0 km
13 6.5 km
14 7.0 km
15 7.5 km
16 8.0 km
17 8.5 km
18 9.0 km
19 9.5 km
20 10.0 km
21 11.0 km
22 12.0 km
23 13.0 km
24 14.0 km
25 15.0 km
26 16.0 km
27 17.0 km
28 18.0 km

TRMM 3B31 can be accessed and ordered from Mirador,

http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?tree=project&dataset=3B31%20%28Version%20007%29:%20Monthly%200.5%20x%200.5%20degree%20Combined%20Rainfall&project=TRMM&dataGroup=Gridded&version=007


Appendix

 

 

Document Actions
NASA Logo - nasa.gov
NASA Privacy Policy and Important Notices
Last updated: Mar 18, 2013 04:32 PM ET