Special Sensor Microwave/Imager (SSM/I) Rainfall Products

Sensor Description:

SSM/I was first launched on boad the Defense Meteorological Satellite Program (DMSP) F8 satellite in June of 1987. The DMSP series satellites are in sun-synchronous polar orbits at an altitude of approximately 830 km. The instrument is a seven channel linearly polarized passive microwave radiometer operating at frequencies of 19.36, 22.235, 37.0, and 85.5 GHz. Detailed specifications for the spacecraft and instrument are given by Hollinger et al. [1987] and Hollinger [1989, 1991].

Algorithm Description:

GPROF 2010: The rainfall algorithm used to compute rainfall estimates from the SSM/I brightness temperature data is the 2010 release of the Goddard PROFiling algorithm (GPROF) [Kummerow et al., 2001, Masunaga and Kummerow, 2005]. The SSM/I version of GPROF is not currently run operationally. Additional information is available on the SSM/I implementation details.

Version Information:
  • GPR08.B4 (GPROF 2008 beta version 4): This is the first output version of the GPROF 2008 algorithm for SSM/I. Note that due to issues with the cloud water path this field is currently set to missing for the SSM/I gridded output files.
  • GPR08.B5 (GPROF 2008 beta version 5): Minor changes were made to the level 2 output, but no significant changes were made to the daily and monthly gridded output products. As a result, the gridded products on this site were not updated to B5.
  • GPR08.B6 (GPROF 2008 beta version 6): B6 is a beta version 6. Changes to the level 2 output include a number of bug fixes along with the following improvements/changes. These include an improvement to the sea-ice edge detection algorithm, the use of higher resolution (0.25x0.25 degree) daily Reynolds SST data, and changes to the channel weights based on individual channel errors. To improve the consistency between rainfall estimates from different sensors a modification was made to the rain screening methodology used in the optimal estimation procedure for retrieving geophysical paramters over non-raining scenes. Finally, for sensors other than TMI several adjustments were made to the apriori databases to improve the consistency in the output rainfall estimates.
  • GPR10.V1 (GPROF 2010 version 1): The apriori database was finalized based on the TRMM version 7 products. In addition, the input SSM/I data was changed to the beta version Fundamental Climate Data Record (FCDR) dataset being developed for NOAA.
  • GPR10.V1a (GPROF 2010 version 1a): A minor change was made to the retrieval over coasts to better screen out artifacts. No changes were made over ocean or land regions.
  • GPR10.V2 (GPROF 2010 version 2): A number of updates were made to the V1 retrieval to improve consistency between sensor and screen for desert on snow-covered regions over land. The land retrievals have been updated and are now available for all the sensors.

Input Brightness Temperature Data:

The rainfall products provided here are computed from the beta version of the CSU Fundamental Climate Data Record (FCDR) brightness temperature dataset being developed for NOAA.

Data Availability:

Rainfall estimates are currently available from all the SSM/I sensors starting with F08 in July of 1987 and continuing through the end of the F13 record in November of 2009. Although there is F15 data available past this data, on August 14, 2006 two radar calibration beacons on board DMSP F15 were activated. These beacons interfere with the 22.235 GHz, resulting in a substantial bias in the brightness temperatures that varies across the scan and over time. We hope to develop a correction to the data to account for the interference at some point, but for the time being F15 rainfall products are only produced through August 13, 2006.

Satellite Start Date End Date
F08 July 9, 1987 December 31, 1991
F10 December 8, 1990 November 14, 1997
F11 December 3, 1991 May 16, 2005
F13 May 3, 1995 November 19, 2009
F14 May 7, 1997 August 23, 2008
F15 February 23, 2000 August 13, 2006

Rainfall Data:

FTP Daily and Monthly Gridded Rainfall Data Files
File Format Specification for Daily Gridded Rainfall Files
File Format Specification for Monthly Gridded Rainfall Files

Rainfall Images:

Create/Display Daily Rainfall Images
Create/Display Monthly Rainfall Images
FTP Pre-rendered Rainfall Images


Get software to read the binary gridded rainfall files.

Additional Documentation/References:

–   Hollinger, J., R. Lo, and G. Poe, Special Sensor Microwave/Imager User's Guide, Naval Research Laboratory, Washington, D.C., Sep. 14, 1987.
–   Hollinger, J. DMSP Special Sensor Microwave/Imager Calibration/Validation, Naval Research Laboratory, Washington, D.C., Vol 1, July 20, 1989.
–   Hollinger, J. DMSP Special Sensor Microwave/Imager Calibration/Validation, Naval Research Laboratory, Washington, D.C., Vol 2, May 20, 1991.
–   Kummerow, C., Y. Hong, W. S. Olson, S. Yang, R. F. Adler, J. McCollum, R. Ferraro, G. Petty, D. B. Shin, and T. T. Wilheit, 2001: The evolution of the Goddard profiling algorithm (GPROF) for rainfall estimation from passive microwave sensors, J. Appl. Meteor., 40, 1801-1820.
–   Masunaga, H. and C. D. Kummerow, 2005: Combined radar and radiometer analysis of precipitation profiles for a parametric retrieval algorithm, J. Atmos. Oceanic Technol., 22, 909-929.

Related Links:

National Geophysical Data Center
Remote Sensing Systems
NOAA Comprehensive Large Array-data Stewardship System (CLASS)