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Summary
The TRMM Microwave Imager (TMI) is a nine-channel passive microwave
radiometer, which builds on the heritage of the Special Sensor
Microwave/Imager (SSM/I) instrument flown aboard the Defense
Meteorological Satellite Program (DMSP) platforms. Microwave radiation
is emitted by the Earth's surface and by water droplets within
clouds. However, when layers of large ice particles are present in
upper cloud regions - a condition highly correlated with heavy
rainfall - microwave radiation tends to scatter at frequencies above
19 GHz. The TMI detects radiation at five frequencies chosen to
discriminate among these processes, thus revealing the likelihood of
rainfall. The key to accurate retrieval of rainfall rates by this
method is the deduction of cloud precipitation consistent with the
radiation measurement at each frequency. The TMI frequencies are
10.65, 19.35, 37 and 85.5 GHz (dual polarization), and 21 GHz
(vertical polarization only).
The Level 1A product file (1A11) is a concatenation of the Level 0
data with a header record and, as such, is reversible to Level 0. The
header record contains information pertaining to orbit times, orbit
number, times of the first scan and number of scans, among other
things. The Level 0 data contain the actual channel data expressed as
"sensor counts." A file contains data for a single orbit with a file
size of about 7 MB (uncompressed). There are 16 files of TMI 1A11
data produced per day.
Spatial coverage is between 38 degrees North and 38 degrees South
owing to the 35 degree inclination of the TRMM satellite.
Contacts for Data Access Information
Goddard DAAC
Hydrology Data Support Team, Code 610.2
NASA Goddard Space Flight Center
Greenbelt, MD 20771
301-614-5224 voice
301-614-5268 fax
Email: help-disc@listserv.gsfc.nasa.gov
Data Center Identification
GSFC-TSS -
Goddard Space Flight Center Distributed Active Archive Center, NASA
References:
Tropical Rainfall Measuring Mission Science Data and Information System (TSDIS)
Interface Control Specification Between the TSDIS and the TSDIS Science User (TSU)
Volume 3: File Specifications for TRMM Products - Level 1,
http://pps.gsfc.nasa.gov/tsdis/Documents/ICSVol3.pdf
Volume 4: File Specifications for TRMM Products - Level 2 and Level 3,
http://pps.gsfc.nasa.gov/tsdis/Documents/ICSVol4.pdf
Document Information
Document Revision Date:Fri May 17 10:10:05 EDT 2002
Document Review Date: Wed May 15 10:24:19 EDT 2002
Document Author: Hydrology Data Support Team
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Atmos Composition
