SSMIS
The Special Sensor Microwave Imager / Sounder (SSMIS) is a 24-channel, 21-frequency, linearly polarized passive microwave radiometer system. The instrument is flown on board the United States Air Force Defense Meteorological Satellite Program (DMSP) F-16, F-17, F-18 and F-19 satellites, which were launched in October 2003, November 2006, October 2009, and April 2014, respectively.{{cite web|title=Special Sensor Microwave/Imager (SSM/I) and Special Sensor Microwave Imager Sounder (SSMIS)|url=https://space.oscar.wmo.int/instruments/view/ssmis|publisher=World Meteorological Office Observing Systems Capability Analysis and Review Tool|accessdate=27 July 2021}} It is the successor to the Special Sensor Microwave/Imager (SSM/I). The SSMIS on the F19 satellite stopped producing useful data in February 2016.{{cite web|url =https://www.space.com/32296-air-force-dmsp-19-weather-satellite-dead.html|title =Air Force Says DMSP-19 Weather Satellite is 'About Dead'|website =Space.com|date =17 March 2016}}
Instrument characteristics
The SSMIS sensor is a passive conically scanning microwave radiometer that combines and extends the current imaging and sounding capabilities of three previously separate DMSP microwave sensors: the SSM/T-1 temperature sounder, the SSMI/T- 2 moisture sounder, and the SSM/I. The SSMIS instrument measures microwave energy at 24 discrete frequencies from 19 to 183 GHz with a swath width of 1700 km.{{cite web|title=SSMI and SSMIS Monitoring and Documentation|url=http://www.ncdc.noaa.gov/oa/rsad/ssmi/swath/|publisher=National Environmental Satellite, Data, and Information Service (NESDIS), NOAA|accessdate=24 December 2010}}
The first SSMIS was launched aboard the DMSP-16 satellite on 18 October 2003.
Due to a manufacturing mistake, the polarization for the channels at 50.3, 52.8, 53.6, 54.4 and 55.5 of the first unit of SSMIS (the one flying on DMSP-16) was reversed. Those five channels detect the vertical polarization rather than the Horizontal polarization detected by the successive units of SSMIS.["Intercalibration between special Sensor Microwave Imager/Sounder and Special Sensor microwave Imager"; B. Yan and F. Weng; IEEE TGRS, 2008, 46, 984]
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|+ Radiometric characteristics of the SSMIS{{Cite journal|last1=Kunkee|first1=David B.|last2=Poe|first2=Gene A.|last3=Boucher|first3=Donald J.|last4=Swadley|first4=Steven D.|last5=Hong|first5=Ye|last6=Wessel|first6=John E.|last7=Uliana|first7=Enzo A.|date=April 2008|title=Design and Evaluation of the First Special Sensor Microwave Imager/Sounder|url=https://ieeexplore.ieee.org/document/4475705|journal=IEEE Transactions on Geoscience and Remote Sensing|volume=46|issue=4|pages=863–883|doi=10.1109/TGRS.2008.917980|bibcode=2008ITGRS..46..863K |s2cid=47668 |issn=1558-0644|url-access=subscription}} [https://archive.today/20121212014645/http://mrain.atmos.colostate.edu/LEVEL1C/level1C_devssmis.html]. |
| scope="col" | Channel #
! scope="col" | Frequency (GHz) ! scope="col" | Polarization ! scope="col" | Along-track resolution (km) ! scope="col" | Cross-track resolution (km) ! scope="col" | Spatial sampling (km x km) ! scope="col" | Instrument noise (K) |
|---|
| 12
| 19.35 | horizontal | 73 | 47 | 45x74 | 0.35 |
| 13
| 19.35 | vertical | 73 | 47 | 45x74 | 0.35 |
| 14
| 22.235 | vertical | 73 | 47 | 45x74 | 0.45 |
| 15
| 37.0 | horizontal | 41 | 31 | 28x45 | 0.22 |
| 16
| 37.0 | vertical | 41 | 31 | 28x45 | 0.22 |
| 1
| 50.3 | horizontal | 17.6 | 27.3 | 37.5 | 0.34 |
| 2
| 52.8 | horizontal | 17.6 | 27.3 | 37.5 | 0.32 |
| 3
| 53.596 | horizontal | 17.6 | 27.3 | 37.5 | 0.33 |
| 4
| 54.4 | horizontal | 17.6 | 27.3 | 37.5 | 0.33 |
| 5
| 55.5 | horizontal | 17.6 | 27.3 | 37.5 | 0.34 |
| 6
| 57.29 | right circular | 17.6 | 27.3 | 37.5 | 0.41 |
| 7
| 59.4 | right circular | 17.6 | 27.3 | 37.5 | 0.40 |
| 19
| 63.283248 ± 0.285271 | right circular | 17.6 | 27.3 | 75 | 2.7 |
| 20
| 60.792668 ± 0.357892 | right circular | 17.6 | 27.3 | 75 | 2.7 |
| 21
| 60.792668 ± 0.357892 ± 0.002 | right circular | 17.6 | 27.3 | 75 | 1.9 |
| 22
| 60.792668 ± 0.357892 ± 0.0055 | right circular | 17.6 | 27.3 | 75 | 1.3 |
| 23
| 60.792668 ± 0.357892 ± 0.016 | right circular | 17.6 | 27.3 | 75 | 0.8 |
| 24
| 60.792668 ± 0.357892 ± 0.050 | right circular | 17.6 | 27.3 | 75 | 0.9 |
| 18
| 91.665 | horizontal | 14 | 13 | 13x16 | 0.19 |
| 17
| 91.665 | vertical | 14 | 13 | 13x16 | 0.19 |
| 8
| 150 | horizontal | 14 | 13 | 13x16 | 0.53 |
| 11
| 183.311 ± 1 | horizontal | 14 | 13 | 13x16 | 0.38 |
| 10
| 183.311 ± 3 | horizontal | 14 | 13 | 13x16 | 0.39 |
| 9
| 183.311 ± 6.6 | horizontal | 14 | 13 | 13x16 | 0.56 |