BackForwardInstrument:  SSMIS 

Instrument details
Acronym SSMIS
Full name Special Sensor Microwave - Imager/Sounder
Purpose Multi-purpose imagery with temperature/humidity sounding channels for improved precipitation
Short description 21 frequencies, 24 channels MW radiometer covering the 54 and 183 GHz bands
Background Replacing and merging SSM/I, SSM/T and SSM/T-2 flown on DMSP up to F15
Scanning Technique Conical: 53.1° zenith angle, swath 1700 km – Scan rate: 31.9 scan/min = 12.5 km/scan
Resolution Changing with frequency, consistent with an antenna diameter of  61 x 66 cm
Coverage / Cycle Global coverage once/day
Mass 96 kg Power 135 W Data Rate 14.2 kbps

 

Providing Agency DoD
Instrument Maturity Flown on operational programme
Utilization Period: 2003-11-20 to ≥2025
Last update: 2014-09-26
Detailed characteristics
Central frequency (GHz) Bandwidth (MHz) Polarisations NEΔT IFOV Pixel
19.35 356 V, H 0.34 K 42.4x70.1 km 25.0 x12.5 km
22.235 407 V 0.45 K 42.4x70.1 km 25.0 x12.5 km
37.0 1580 V, H 0.24 K 27.5x44.2 km 25.0 x12.5 km
50.3 380 H 0.21 K 17.5x25.8 km 37.5 x12.5 km
52.8 389 H 0.20 K 17.5x25.8 km 37.5 x12.5 km
53.596 380 H 0.21 K 17.5x25.8 km 37.5 x12.5 km
54.4 382 H 0.20 K 17.5x25.8 km 37.5 x12.5 km
55.5 391 H 0.22 K 17.5x25.8 km 37.5 x12.5 km
57.29 330 RC 0.26 K 17.5x25.8 km 37.5 x12.5 km
59.4 239 RC 0.25 K 17.5x25.8 km 37.5 x12.5 km
60.792668 ± 0.357892 ± 0.050 106 RC 0.38 K 17.5x25.8 km 75.0 x12.5 km
60.792668 ± 0.357892 ± 0.016 29.4 RC 0.37 K 17.5x25.8 km 75.0 x12.5 km
60.792668 ± 0.357892 ± 0.006 10.4 RC 0.58 K 17.5x25.8 km 75.0 x12.5 km
60.792668 ± 0.357892 ± 0.002 5.2 RC 0.86 K 17.5x25.8 km 75.0 x12.5 km
60.792668 ± 0.357892 2.7 RC 1.18 K 17.5x25.8 km 75.0 x12.5 km
63.283248 ± 0.285271 2.7 RC 1.23 K 17.5x25.8 km 75.0 x12.5 km
91.655 2829 V, H 0.19 K 13.1x14.4 km 12.5 x12.5 km
150 3284 H 0.53 K 13.1x14.4 km 12.5 x12.5 km
183.31 ± 6.6 1025 H 0.56 K 13.1x14.4 km 12.5 x12.5 km
183.31 ± 3.0 2038 H 0.39 K 13.1x14.4 km 12.5 x12.5 km
183.31 ± 1.0 3052 H 0.38 K 13.1x14.4 km 12.5 x12.5 km
Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Instrument classification
  • Earth observation instrument
  • Passive microwave radiometer
  • Conical scanning microwave radiometer
Mission objectives
Primary mission objectives
  • Precipitation intensity at surface (liquid or solid)
  • Sea-ice cover
  • Wind speed over the surface (horizontal)
Secondary mission objectives
  • Atmospheric temperature
  • Cloud ice (total column)
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Tentative Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
VariableRelevance for measuring this variableOperational limitationsExplanation
Accumulated precipitation (over 24 h)4 - fairPoor time sampling. Time sampling to be interpolated by GEO. MW channels around 19, 23, 37 and 90 GHz, and in 54 and 183 GHz bands
Atmospheric temperature3 - highCoarse vertical resolution. Many MW channels in the 54 GHz band. Nearly all-weather sounding
Cloud drop effective radius4 - fairNo specific limitation. MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud ice4 - fairNo specific limitation. MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud ice (total column)3 - highNo specific limitation. MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud ice effective radius4 - fairNo specific limitation. MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud liquid water (CLW)3 - highNo specific limitation. MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud liquid water (CLW) total column2 - very highNo specific limitation. MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Downward long-wave irradiance at Earth surface5 - marginalHighly indirect. MW channels in bands 54 and 183 GHz to account for downward cloud radiation
Freezing level height in clouds3 - highNo specific limitation. MW channels in the 54 GHz band. Inference from the temperature profile
Long-wave Earth surface emissivity5 - marginalLong time series needed. MW channels around 19, 37 and 90 GHz. Emissivity across this MW range inferred by statistical analysis
Melting layer depth in clouds3 - highNo specific limitation. MW channels in the 54 GHz band. Inference from the temperature profile
Precipitation intensity at surface (liquid or solid)3 - highNo specific limitation. MW channels around 19, 23, 37 and 90 GHz; and in bands 54 and 183 GHz, insensitive to surface emissivity and providing information on atmospheric structure
Sea-ice cover3 - highNo specific limitation. MW channels around 19, 37 and 90 GHz
Sea-ice type5 - marginalNo specific limitation. MW channels around 19, 37 and 90 GHz. Type interpreted as age/roughness
Snow cover3 - highCoarse spatial resolution. MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow
Snow status (wet/dry)3 - highCoarse spatial resolution. MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow
Snow water equivalent4 - fairCoarse spatial resolution. Ground stations network needed. MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow
Specific humidity4 - fairCoarse vertical resolution. MW channels in the 183 GHz band, and 54 GHz for temperature and liquid water corrections
Integrated Water Vapour (IWV)1 - primaryNo specific limitation. MW channel(s) in the water vapour bands around 23 and 183 GHz
Upward long-wave irradiance at Earth surface4 - fairHighly indirect. MW channels is the 54 and 183 GHz bands to infer the impact of clouds on the upward LW radiation
Wind speed over the surface (horizontal)4 - fairOver sea only. MW channels around 19 and 37 GHz