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Project Information
Data Processing
Data Access
Data set Validation
Documentation
References
Contacts
Acknowledgment
Disclaimer
Related Sites
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Introduction
The U.S. Department of Agriculture’s Foreign Agricultural Service (USDA-FAS), in cooperation with the National Aeronautics and Space Administration’s Goddard Earth Sciences Data and Information Services Center Distributed Active Archive Center (GES DISC DAAC), are routinely using satellite-derived data to monitor precipitation around the world. This project is unique, being the first of its kind to utilize near-real time global satellite precipitation data in an operational manner. Satellite precipitation products are produced by NASA via a semi-automated process and made accessible from this Web site for USDA and public viewing. Monitoring precipitation for agriculturally important areas around the world will greatly assist the USDA-FAS to quickly locate regional weather events, as well as improve crop production estimates.
Data Processing
The NASA Goddard Space Flight Center (GSFC) system to produce the "TRMM and Other Data" estimates in real time was developed to apply new concepts in merging quasi-global precipitation estimates and to take advantage of the increasing availability of input data sets in near real time. The overall system is referred to as the real-time TRMM Multi-Satellite Precipitation Analysis (TMPA-RT). The TMPA-RT is run quasi-operationally on a best-effort basis at the TRMM Science Data and Information System (TSDIS), with on-going scientific development by the research team led by Dr. Robert Adler in the GSFC Laboratory for Atmospheres. Estimates are posted to the Web about six hours after observation time, although processing issues may delay or prevent this schedule. Due to the experimental nature of these estimates, users are encouraged to report their experiences with the data, and they should expect episodic upgrades or outages as the system develops.
There are three "TRMM and Other Data" products: (1) 3B40RT (High Quality, or HQ), which is a merger of all available TMI, SSM/I, AMSR-E, and AMSU-B microwave precipitation estimates into a "high-quality" (HQ) precipitation estimate; (2) 3B41RT (Variable Rain-rate Infrared, or VAR) precipitation estimates from geostationary infrared (IR) observations using spatially and temporally varying calibration by the HQ; and (3) 3B42RT (Merger of HQ and VAR), which is a merger of 3B40RT (HQ) and 3B41RT (VAR). The current scheme is simple replacement, i.e., for each gridbox, the HQ value is used if available; otherwise, the VAR value is used. All fields are 1440x480 gridboxes (0-360 deg. E, 60 deg. N-S). The first grid box center is at 0.125 degree E and 59.875 degree N. Files are produced every three hours on synoptic observation hours (00 UTC, 03 UTC, ..., 21 UTC), using that hour's 3B40RT and 3B41RT data sets. Valid estimates are only provided in the band 50 degree N-S.
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Data Access
The 3B42RT is the specific product available from the NASA GES-DISC Interactive Online Visualization and Analysis Infrastructure-Agriculture (Giovanni-Ag; http://agdisc.gsfc.nasa.gov/Giovanni/). Giovanni is the underlying infrastructure for a growing family of Web interfaces that allows users to easily view and analyze gridded data interactively online without having to download any data. As implemented in this project, Giovanni output plots of the 3B42RT precipitation data are accessed seamlessly from within the context of FAS’ Crop Explorer (i.e., a retrieved Giovanni plot shows precipitation for the same geographical area and time period as those of current interest to the Crop Explorer user).
Access to the digital data is by anonymous ftp to trmmopen.nascom.nasa.gov. Under subdirectory pub/merged, there are three directories: (1) CombinedMicro (3B40RT), (2) CalibratedIR (3B41RT), and (3) MergeIRMicro (3B42RT).
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Data set Validation
The TMPA-RT data sets represent a new initiative and should be considered experimental. Formal validation studies are underway but not yet available. The primary limitations on the HQ (3B40RT) are the sparse sampling by the collection of passive-microwave satellites and algorithm drop-outs in regions with icy or frozen surface. The infrared results (3B41RT) are designed to emulate the microwave results as closely as possible, so known deficiencies in the microwave will likely be reflected in the infrared as well. In addition, it is well known that infrared algorithms of the kind used here have large random errors at the fine time and space scales provided. However, the infrared estimates are expected to match the histogram of the microwave estimates, so that user-specified averaging should yield approximately unbiased results. Finally, the combined microwave-IR fields (3B42RT) contain data boundaries between the regions of microwave and IR coverage. Instantaneously, the boundaries are usually subtle; but they are more noticeable in movie loops, because the regions of coverage change with each image. The TMPA-RT developers encourage users to report successes and problems in applying these data sets to their particular applications.
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Additional Documentation
Users should refer to the detailed documentation (3B4XRT_doc) and programming examples at the anonymous FTP site, ftp://trmmopen.nascom.nasa.gov/pub/merged/software, for additional details.
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References or, link to ftp://trmmopen.nascom.nasa.gov/pub/merged/3B4XRT_doc
Grody, N.C., 1991: Classification of snow cover and precipitation using
the Special Sensor Microwave/Imager (SSM/I). J. Geophys. Res., 96,
7423-7435.
Hollinger, J., R. Lo, G. Poe, and J. Peirce, 1987. Special Sensor
Microwave/Imager UserÕs Guide, Naval Res. Lab., Washington, DC.
Hollinger, J.P., J.L. Pierce, and G.A. Poe, 1990: SSM/I instrument
evaluation. IEEE Trans. Geosci. Remote Sens., 28, 781-790.
Huffman, G.J., 1997: Estimates of root-mean-square random error
contained in finite sets of estimated precipitation. J. Appl.
Meteor., 36, 1191-1201.
Huffman, G.J., R.F. Adler, D.T. Bolvin, G. Gu, E.J. Nelkin, K.P. Bowman,
E.F. Stocker, D.B. Wolff, 2006: The TRMM Multi-satellite Precipitation
Analysis: Quasi-Global, Multi-Year, Combined-Sensor Precipitation
Estimates at Fine Scale. / /J. Hydrometeorology, submitted.
Huffman, G.J., R.F. Adler, S. Curtis, D.T. Bolvin, and E.J. Nelkin,
2005: Global Rainfall Analyses at Monthly and 3-Hr Time Scales.
Chapter 4 of Measuring Precipitation from Space: EURAINSAT and
the Future, V. Levizzani, P. Bauer, and J. Turk, Ed., Springer
Verlag (Kluwer Academic Pub. B.V.), Dordrecht, The Netherlands,
accepted. [Invited paper]
Huffman, G.J., R.F. Adler, E.F. Stocker, D.T. Bolvin, and E.J. Nelkin,
2003: Analysis of TRMM 3-hourly multi-satellite precipitation
estimates computed in both real and post-real time. Combined
Preprints CD-ROM, 83rd AMS Annual Meeting. Paper P4.11 in 12th
Conf. on Sat. Meteor. and Oceanog., 9-13 Feb. 2003, Long Beach,
CA, 6 pp.
Janowiak, J.E., and P.A. Arkin, 1991: Rainfall variations in the
tropics during 1986-1989. J. Geophys. Res., 96, 3359-3373.
Joyce, R.J., J.E. Janowiak, P.A. Arkin, and P. Xie, 2004: CMORPH: A
method that produces global precipitation estimates from passive
microwave and infrared data at 8 km, hourly resolution. J.
Climate, 5, 487-503.
Joyce, R.J., J.E. Janowiak, G.J. Huffman, 2001: Latitudinal and
Seasonal Dependent Zenith Angle Corrections for Geostationary
Satellite IR Brightness Temperatures. J. Appl. Meteor., 40(4),
689-703.
Kummerow, C., W.S. Olson, and L. Giglio, 1996: A simplified scheme
for obtaining precipitation and vertical hydrometeor profiles from
passive microwave sensors. IEEE Trans. Geosci. Remote Sens., 34,
1213-1232.
Kummerow, C., W. Barnes, T. Kozu, J. Shiue, and J. Simpson, 1998: The
Tropical Rainfall Measuring Mission (TRMM) Sensor Package. J. Atmos.
and Oceanic Tech., 15(3), 809-817.
Olson, W. S., C. D. Kummerow, Y. Hong, and W.-K. Tao, 1999: Atmospheric
latent heating distributions in the tropics derived from satellite
passive microwave radiometer measurements. J. Appl. Meteor., 38,
633-664.
Smith, T.M., P.A. Arkin, G.J. Huffman, and J.J. Bates, 2004:
Estimating Bias of Satellite-Based Precipitation Estimates. Proc.
of the 2nd Internat. Precip. Working Group Workshop, 25-28 October
2004, Monterey, CA, to appear.
Sorooshian, S., K.-L. Hsu, X. Gao, H.V. Gupta, B. Imam, and D.
Braithwaite 2000: Evaluation of PERSIANN system satellite-based
estimates of tropical rainfall. Bull. Amer. Meteor. Soc., 81,
2035-2046.
Spencer, R.W., 1993: Global oceanic precipitation from the MSU during
1979-92 and comparisons to other climatologies. J. Climate, 6,
1301-1326.
Turk, F.J., G.D. Rohaly, J. Hawkins, E.A. Smith, F.S. Marzano, A.
Mugnai, and V. Levizzani, 1999: Meteorological applications of
precipitation estimation from combined SSM/I, TRMM and infrared
geostationary satellite data. Microwave Radiometry and Remote
Sensing of the Earth's Surface and Atmosphere, P. Pampaloni and S.
Paloscia Eds., VSP Int. Sci. Publ., 353-363.
Weng, F., L. Zhao, R. Ferraro, G. Poe, X. Li, and N. Grody, 2003:
Advanced Microwave Sounding Unit Cloud and Precipitation
Algorithms. Radio Sci., 38, 8068Ð8079.
Wentz, F.J., and R.W. Spencer, 1998: SSM/I rain retrievals within a
unified all-weather ocean algorithm. J. Atmos. Sci., 55(9),
1613-1627.
Zhao, L., and F. Weng, 2002: Retrieval of Ice Cloud Parameters Using
the Advanced Microwave Sounding Unit. J. Appl. Meteor., 41, 384-
395.
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For more information, contact:
Dr. William Teng
NASA GSFC DAAC
Code 610.2
Greenbelt, MD 20771
USA
Tel: (301)614-5164
Fax: (301) 614-5268
teng@disc.gsfc.nasa.gov
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Acknowledgment
The TMPA-RT data are "freely available." However, the following acknowledgment should be made if …
“TMPA-RT satellite precipitation data were provided by the NASA/Goddard Space Flight Center's Laboratory for Atmospheres and TSDIS, which develop and compute the TMPA-RT as a contribution to TRMM."
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Disclaimer
Use of Data and Product
The information on government servers are in the public domain, unless specifically annotated otherwise, and may be used freely by the public. Before using information obtained from this server special attention should be given to the date & time of the data and products being displayed. This information shall not be modified in content and then presented as official government material.
The user assumes the entire risk related to its use of this data. USDA is providing this data "as is," and USDA disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will USDA be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data.
As required by 17 U.S.C. 403, third parties producing copyrighted works consisting predominantly of the material appearing in USDA Web pages must provide notice with such work(s) identifying the USDA material incorporated and stating that such material is not subject to copyright protection.
Any reference from USDA Web server service to any non-government entity, product, service or information does not constitute an endorsement or recommendation by the USDA or any of its' field offices or employees. We are not responsible for the contents of any "off-site" web pages referenced from USDA servers.
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Related Sites
Agriculture REASoN Project Portal:
http://disc.gsfc.nasa.gov/agriculture/index.shtml
AMSR instrument:
http://www.ghcc.msfc.nasa.gov/AMSR/
AMSU-B instrument:
http://www2.ncdc.noaa.gov/docs/klm/html/c3/sec3-4.htm
in the NOAA KLM User's Guide (September 2000 revision): http://www2.ncdc.noaa.gov/docs/klm/index.htm
GSFC:
http://www.nasa.gov/centers/goddard/home/index.html
IPWG Validation for Australia:
http://www.bom.gov.au/bmrc/wefor/staff/eee/SatRainVal/sat_val_aus.html
IPWG Validation for U.S.:
http://www.cpc.ncep.noaa.gov/products/janowiak/us_web.shtml
IPWG Validation for Western Europe:
http://kermit.bham.ac.uk/~kidd/ipwg_eu/ipwg_eu.html
MAPB Precipitation Page:
http://precip.gsfc.nasa.gov/
TMPA-RT Data:
ftp://trmmopen.nascom.nasa.gov/pub/merged/
NASA:
http://www.nasa.gov/
TRMM home:
http://trmm.gsfc.nasa.gov/
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