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TRMM Microwave Imager (TMI) 2A12

Data Access:
TRMM Microwave Imager (TMI) Level 2A Hydrometeor Profile Product

2A12 (Version 007): 

http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?tree=project&dataset=2A12%20%28Version%20007%29:%20Hydrometeor%20Profile%20%28TMI%29&project=TRMM&dataGroup=Orbital&version=007


Latent heating (LH) products are only available over ocean.  Please use the radar or combined LH products over land and coastal area

Contents:

Summary

2A-12, "TMI Pro ling", generates surface rainfall and vertical hydrometeor pro les on a pixel by pixel basis from the TRMM Microwave Imager (TMI) brightness temperature data using the Goddard Pro ling algorithm GPROF2008. Because the vertical information comes from a radiometer, it is not written out in independent vertical layers like the TRMM Precipitation Radar. Instead, the output is referenced to one of 100 typical structures for each hydrometeor or heating pro le. These vertical structures are referenced as clusters in the output structure. Vertical hydrometeor pro les can be reconstructed to 28 layers by knowing the cluster number (i.e. shape) of the pro le and a scale factor that is
written for each pixel.
GPROF 2008 (2A12, V7) vs GPROF 2004 (2A12, V6)
(A short explanation of the diff erences)
The basic change from 2A12, V6 (corresponding to GRPOF2004) and 2A12, V7 (Corresponding to GPROF2008) is the use of the observed databases instead of CRM databases. GPROF 2004 used a set of eight cloud resolving model simulations to create the a-priori databases for the Bayesian retrieval scheme. This methodology had issues over oceans due primarily to a lack of completeness or representativeness of this database. GPROF 2008 replaced these simulations with combined radar/radiometer/CRM retrievals that are supposed to better represent the actual pro les seen over oceans. One year of combined retrievals (detailed in Kummerow et al., J. Atmos. and Oceanic Tech., 2010) are used to construct the a-priori database. Note that while the a-priori database in GPROF2004 was strati ed by SST, the GPROF2008 database is strati ed by both SST and total precipitable water (TPW). The retrieval was also changed over land. Here, new regressions have been established to match PR rainfall. These are done separately for convective
and stratiform precipitation. The regressions are global. Changes to the algorithm led to some natural changes in the output format. Below is a basic description of the new or modi ed felds.

Data Flow Description

TMI Level 1A ==> 1B11 Calibrated TMI brightness temperatures ==> 2A12 TMI Rainfall Structure

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

Data Set Description

Data Characteristics

TRMM 2A12 (TMI) Data Characteristics
  Pre-boost (before 08-07-2001) Post-boost (after 08-24-2001)
Temporal Coverage Start Date: 12-08-1997
Stop Date: 08-07-2001
Start Date: 08-24-2001
Stop Date: -
Geographic Coverage Latitude: 38°S - 38°N
Longitude:180°W - 180°E
Latitude: 38°S - 38°N
Longitude:180°W - 180°E
Vertical Coverage Surface - 18 km Surface - 18 km
Temporal Resolution About 91.5 minutes per orbit
About 16 orbits per day
More information about revisit frequency
About 92.5 minutes per orbit
About 16 orbits per day
More information about revisit frequency
Horizontal Resolution 4.4 km at 85.5 GHz 5.1 km at 85.5 GHz
Vertical Resolution 0.5 km from surface to 4 km
1.0 km from 4 to 6 km
2.0 km from 6 to 10 km
4.0 km from 10 to 18 km
0.5 km from surface to 4 km
1.0 km from 4 to 6 km
2.0 km from 6 to 10 km
4.0 km from 10 to 18 km
Scan Characteristics Swath Width: 760 km
Pixels/Scan: 208
Scans/Second (SS): 36.100/60
Seconds/Orbit (SO): 5490
Average Scans/Orbit: nscan = SS*SO+100 = 2991
Swath Width: 878 km
Pixels/Scan: 208
Scans/Second (SS): 36.100/60
Seconds/Orbit (SO): 5550
Average Scans/Orbit: nscan = SS*SO+100 = 3023
Average File Size Compressed: ~11 MB Compressed: ~11 MB
File Type HDF HDF

Data Format Structure

The following table summarizes the contents and structure of the TMI rain profile (2A12) product. Further information can be found in File Specifications for TRMM Products - Version 7.00

Data Format Structure for 2A12, TMI Profiling
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.
Swath Structure Char Attribute 5,000 - - - - Specifications for the swath geometry.
Scan Time Vdata Table 9 nscan - - - Time associated with each scan.
Latitude Float SDS 4 npixel*nscan - - degree Earth location of the center of the IFOV at the altitude of the earth ellipsoid. The first dimension is latitude and longitude, in that order. The next dimensions are numbers of pixels and scans.
Longitude Float SDS 4 npixel*nscan - - degree Earth location of the center of the IFOV at the altitude of the earth ellipsoid. The first dimension is latitude and longitude, in that order. The next dimensions are numbers of pixels and scans.
Scan Status Vdata Table 21 nscan - - - Status of each scan.
Navigation Vdata Table 88 nscan - - - Spacecraft geocentric information.
Data Flag Integer SDS 1 npixel*nscan - - - Indicates the quality of data.
Rain Flag Integer SDS 1 npixel*nscan - - - Indicates if rain is possible
>=0 : rain is possible;
<0 : non-raining.
Surface Flag Integer SDS 1 npixel*nscan - 0 ~ 3 - Indicates the type of surface
0-ocean; 1-land; 2-coast; 3-other.
Surface Rain Float SDS 4 npixel*nscan - 0.0 ~ 3000.0 mm/h Instantaneous rain rate at the surface for each pixel.
Convective Precipitation Float SDS 4 npixel*nscan - 0.0. ~ 3000.0 mm/h Instantaneous convective precipitation rate at the surface for each pixel.
Confidence Float SDS 4 npixel*nscan - 0.0 ~ 300.0 K Associated with the surface rain, and measured as an rms deviation in temperatures.
Cloud  Water Float SDS 4 nlayer*npixel*nscan see array 0.00 ~ 10.00 g m-3 Cloud water content for each pixel at 28 layers.
Rain Water Float SDS 4 nlayer*npixel*nscan see array 0.00 ~ 10.00 g m-3 Rain water content for each pixel at 28 layers.
Cloud Ice Float SDS 4 nlayer*npixel*nscan see array 0.00 ~ 10.00 g m-3 Cloud ice content for each pixel at 28 layers.
Snow Water Float SDS 4 nlayer*npixel*nscan see array 0.00 ~ 10.00 g m-3 Snow water content for each pixel at 28 layers.
Graupel Water Float SDS 4 nlayer*npixel*nscan see array 0.00 ~ 10.00 g m-3 Graupel water content for each pixel at 28 layers.
Latent Heating Float SDS 4 nlevel*npixel*nscan see array -256 ~ 256 °C/hour Latent heating release for each pixel at 28 levels.
Note: nlevel: the number of latent heating levels (28)
nlayer: the number of profiling layers (28)
TRMM 2A12 can be accessed and ordered from Mirador,

http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?tree=project&dataset=2A12%20%28Version%20007%29:%20Hydrometeor%20Profile%20%28TMI%29&project=TRMM&dataGroup=Orbital&version=007

For more details about the data structures, File Specifications for TRMM Products - Version 7.00

Papers associated with the over-ocean latent heating algorithm:

Olson, W. S., C. D. Kummerow, S. Yang, G. W. Petty, W.-K. Tao, T. L. Bell, S.
A. Braun, Y. Wang, S. E. Lang, D. E. Johnson and C. Chiu. 2006: Precipitation and latent heating distributions from satellite passive microwave radiometry.

Part I: Improved method and uncertainties. J. Appl. Meteor. and Climatol., 45, 702-720.

Yang, S., W. S. Olson, J.-J. Wang, T. L. Bell, E. A. Smith and C. D. Kummerow.

2006: Precipitation and latent heating distributions from satellite passive microwave radiometry.

Part II: Evaluation of estimates using independent data.
J. Appl. Meteor. and Climatol., 45, 721-739.


Appendix

TRMM 2A12 Scan Time
Name Format Description
Year 2-byte integer 4-digit year, e.g., 1998
Month 1-byte integer The month of the Year
Day of Month 1-byte integer The day of the Month
Hour 1-byte integer The hour (UTC) of the Day
Minute 1-byte integer The minute of the Hour
Second 1-byte integer The second of the Minute
Day of Year 2-byte integer The day of the Year

TRMM 2A12 Data Flag Specific Values
Value Description
0 Good data quality
-9 Channel brightness temperature outside valid range
-15 The neighboring 5 x 5 pixel array is incomplete due to edge or bad data quality
-21 Surface type invalid
-23 Date time invalid
-25 Latitude or longitude invalid

28 Vertical Profiling 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
28 Vertical Heating Levels
Level Index Level 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
     

 

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Last updated: Aug 13, 2014 11:35 AM ET