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. See table below for channel details.
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: 2004 to 2025
Last update: 2022-12-19
Detailed characteristics

No.

Central frequency (GHz)

Bandwidth (MHz)

Polarisation

NEΔT

IFOV

Pixel

12

19.35

355

H

0.34 K

42.4x70.1 km

25.0 x12.5 km

13

19.35

356.7

V

0.34 K

42.4x70.1 km

25.0 x12.5 km

14

22.235

407.5

V

0.45 K

42.4x70.1 km

25.0 x12.5 km

15

37.0

1545

H

0.24 K

27.5x44.2 km

25.0 x12.5 km

16

37.0

1615

V

0.24 K

27.5x44.2 km

25.0 x12.5 km

1

50.3

380

H

0.21 K

17.5x25.8 km

37.5 x12.5 km

2

52.8

388.8

H

0.20 K

17.5x25.8 km

37.5 x12.5 km

3

53.596

380

H

0.21 K

17.5x25.8 km

37.5 x12.5 km

4

54.4

382.5

H

0.20 K

17.5x25.8 km

37.5 x12.5 km

5

55.5

391.3

H

0.22 K

17.5x25.8 km

37.5 x12.5 km

6

57.29

330

RC

0.26 K

17.5x25.8 km

37.5 x12.5 km

7

59.4

238.8

RC

0.25 K

17.5x25.8 km

37.5 x12.5 km

24

60.792668 ± 0.357892 ± 0.050

26.4816

RC

0.38 K

17.5x25.8 km

75.0 x12.5 km

23

60.792668 ± 0.357892 ± 0.016

7.3152

RC

0.37 K

17.5x25.8 km

75.0 x12.5 km

22

60.792668 ± 0.357892 ± 0.006

2.6239

RC

0.58 K

17.5x25.8 km

75.0 x12.5 km

21

60.792668 ± 0.357892 ± 0.002

1.2883

RC

0.86 K

17.5x25.8 km

75.0 x12.5 km

20

60.792668 ± 0.357892

1.3556

RC

1.18 K

17.5x25.8 km

75.0 x12.5 km

19

63.283248 ± 0.285271

1.3584

RC

1.23 K

17.5x25.8 km

75.0 x12.5 km

17

91.655

1411

V

0.19 K

13.1x14.4 km

12.5 x12.5 km

18

91.655

1418

H

0.19 K

13.1x14.4 km

12.5 x12.5 km

8

150 ± 1.25

1642

H

0.53 K

13.1x14.4 km

12.5 x12.5 km

9

183.31 ± 6.6

1526

H

0.56 K

13.1x14.4 km

12.5 x12.5 km

10

183.31 ± 3.0

1019

H

0.39 K

13.1x14.4 km

12.5 x12.5 km

11

183.31 ± 1.0

512.5

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
WIGOS Subcomponents
  • Subcomponent 1
  • MW sounders [in SSO]
  • MW sounder [in SSO]
  • MW imagery [in SSO]
  • MW imager [in SSO]
  • MW cross-track upper stratospheric and mesospheric sounders
  • MW cross-track upper stratospheric and mesospheric sounder
Mission objectives
Primary mission objectives
  • Precipitation intensity at surface (liquid or solid)
  • Sea-ice cover
  • Wind speed (near surface)
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
Note: * Primary mission objective.
VariableRelevance for measuring this variableOperational limitationsExplanation
Accumulated precipitation3 - highPoor 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 temperature2 - very highCoarse vertical resolution.Many MW channels in the 54 GHz band. Nearly all-weather sounding
Cloud drop effective radius5 - marginalHighly indirect.MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud ice3 - highNo specific limitation.MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud ice Total Column3 - highNo specific limitation.MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud ice effective radius2 - very highNo specific limitation.MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz
Cloud liquid water (CLW)2 - very 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
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)2 - very highCoarse spatial resolution.MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow
Snow water equivalent2 - very highCoarse 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 humidity2 - very highCoarse 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 surface5 - marginalHighly indirect.MW channels is the 54 and 183 GHz bands to infer the impact of clouds on the upward LW radiation
Wind speed (near surface)*4 - fairOver sea only.MW channels around 19 and 37 GHz
Sea-ice cover*3 - highNo specific limitation.MW channels around 19, 37 and 90 GHz
Sea-ice type4 - fairNo specific limitation.MW channels around 19, 37 and 90 GHz. Type interpreted as age/roughness