Only F15 And F13 Continue To Operate
The NOAA/NASA Pathfinder Program Special Sensor Microwave/Imager (SSM/I) Level 3 Equal-Area Scalable Earth-Grid (EASE-Grid) Brightness Temperatures consist of gridded data in one of three projections, Northern Hemisphere, Southern Hemisphere and full global. The data gridding technique maximizes the radiometric integrity of the original brightness temperature values, maintains high spatial and temporal precision, and involves no averaging of original swath data. Coverage is global and begins 9 July 1987; processing is ongoing. Resolution is 25 km for all channels; 85 GHz channels are also provided at 12.5 km resolution. There are 18 brightness temperature files per day for a given projection, and two corresponding time files. Data are contained in flat binary files, either one grid per file consisting of 2-byte integer arrays of brightness temperatures in tenths of kelvins, or in the case of time files, 1-byte integer arrays consisting of Coordinated Universal Time (UTC) in tenths of hours. Ocean surface wind speeds, water vapor, cloud water and rain rates are available as gridded binary files with 0.25 deg resolution for both ascending and descending orbit passes. The data are available from July 1987 for F8, F10, F11, F13, F14 and F15. Currently operating instruments are on F13 and F15, but F15 data should not be used for climatological study due to interference problems from an onboard radio beacon. All instruments were carefully intercalibrated prior to applying the same algorithm yielding consistently processied products for use in climate research. In addition, intercalibration and consistency in processing crosses to other microwave radiometers such as TMI and AMSR-E, resulting in a suite of microwave products extending over more than 20 years. More information about processing and algorithms can be found at Processing of data is ongoing. Data are available via FTP as processing is completed. Users can order temporal or spatial subsets of data with the Graphical Interface for Subsetting, Mapping, and Ordering (GISMO) Web-based tool. Users can also request the complete data set or a long time series of data. Users may also order historical data on CD-ROM, while supplies last.
See availability above and
Satellite Instruments
The Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager(SSM/I) became operational in July 1987 on the F-8 satellite. Subsequent SSM/I's have been flown on the F- 10 (November 1990), F-11 (December 1991), F-12 (August 1994), F-13 (March 1995), F-14 (April 1997) and most recently, F-15 (January 2000) satellites. At present, NESDIS receives data from the F-13, and F-15 satellites. F-15 data should not be used for climate studies after Aug. 2006. F12 SSM/I did not operate. There are no SSM/I data for F12. The SSM/I is a seven channel passive microwave radiometer operating at four frequencies (19,35, 22,235, 37.0, and 85.5 GHz) and dual-polarization (except at 22.235 GHz which is V-polarization only). It should be noted that the SSM/I is replaced by an advanced sensor, the SSMIS (Special Sensor Microwave Imager Sounder) on the F-16 satellite (launched October 2003) and F17 (launched Nov 2006). The F-16 data is now available through the NESDIS CLASS system. There should be little impact on the suite of hydrological products described here, as the primary channels used are very similar between the SSM/I and SSMIS.
Frank Wentz
Remote Sensing Systems
1101 College Av Suite 220 Santa Rosa, CA
Measurment TypeVisible/IR-imager
Platform TypeDefense Meteorological Satellite Program Satellites
OrbitSun synchronous
Spectral Coverage19 - 85 GHz, 4 bands, 3 with dual polarization
Scan PatternPush broom
Variablesprecipitation, sea ice, ocean wind, atmospheric moisture
Repeat Time
Wavelength to nm
Number of Bands
Temporal Coverage
Swath Width
See web pages
SSM/I is an operational instrument that is being replaced by a new instrument SSMIS in 2006 and 2007.
12 Nov 2009 11:49