TRMM Microwave Imager (TMI) Rainfall Products
The TMI is a nine-channel passive microwave radiometer based upon
the Special Sensor Microwave/Imager (SSM/I). The key differences
are the addition of a pair of 10.7-GHz channels with horizontal
and vertic al polarizations and a frequency change of the water
vapor channel from 22.235 to 21.3 GHz. This change off the center
of the water vapor line was made in order to avoid saturation in the
tropical orbit of TRMM. In addition, the TMI has significantly
higher spatial resolution than SSM/I due to the lower orbit of the
TMI specific details:
Information from the additional 10.65 GHz channels is used for
intense rainfall scenes where the higher frequency channels begin
to saturate. The change in the water vapor channel to 21.3 GHz also
varies from the SSM/I retrieval as does the resolution of the sensor.
The higher resolution of the TMI sensor (30x18 km vs. 69x43 km for
the 19 GHz channels) decreases the impact of partial beam-filling,
although it remains a significant issue.
Input Brightness Temperature Data:The rainfall products provided here are computed from the Level 1C brightness temperature dataset.
The TRMM satellite was launched on November 27, 1997 with rainfall
estimates available from December 8, 1997 through to the present.
Because the inclination of TRMM is only 35° the rainfall
estimates from TMI are limited to the tropics, extending from
approximately 38°S to 38°N.
Daily and monthly gridded rainfall data is available via ftp.
Details on the file format are also provided.
FTP Rainfall Data
File Format for Daily Gridded Rainfall Files
File Format for Monthly Gridded Rainfall Files
Browse images in png format have been created for both the daily
and monthly gridded rainfall data products.
Create Daily Rainfall Images
Create Monthly Rainfall Images
FTP Pre-rendered Rainfall Images
Software to read the binary data files is available in both C and
Kummerow, C., W. Barnes, T. Kozu, J. Shiue, and J. Simpson, 1998: The Tropical Rainfall Measuring Mission (TRMM) sensor package, J. Atmos. Oceanic Technol., 15, 809-817.
Kummerow, C. and Coauthors, 2000: The status of the Tropical Rainfall Measuring Mission (TRMM) after two years in orbit, J. Appl. Meteor., 39, 1965-1982.