BackForwardInstrument:  GMI (core) 

Instrument details
Acronym GMI (core)
Full name GPM Microwave Imager
Purpose Multi-purpose imager, with emphasis on precipitation
Short description 8 frequencies / 13 channels [see detailed characteristics below]
Background Evolution of TMI on TRMM
Scanning Technique Conical: 53° zenith angle; useful swath: 850 km - Scan rate: 32 scan/min = 13.4 km/scan
Resolution Changing with frequency, consistent with an antenna diameter of  1.2 m (only partially illuminated at higher frequencies)
Coverage / Cycle Near-global coverage in 2 days; high latitudes (> 70°) not covered.
Mass 150 kg Power 140 W Data Rate 25 kbps

 

Providing Agency NASA
Instrument Maturity Backed by strong heritage
Utilization Period: 2014-09-04 to ≥2020
Last update: 2019-11-14
Detailed characteristics

No.

Central frequency (GHz)

Bandwidth (MHz)

Polarisation

NEΔT

IFOV

Pixel

1

10.65

100

V

0.96 K

19x32 km

12x13.4 km

2

10.65

100

H

0.96 K

19x32 km

12x13.4 km

3

18.7

200

V

0.84 K

11x18 km

6.0x13.4 km

4

18.7

200

H

0.84 K

11x18 km

6.0x13.4 km

5

23.8

400

V

1.05 K

9.2x15 km

6.0x13.4 km

6

36.5

1000

V

0.65 K

8.6x14 km

6.0x13.4 km

7

36.5

1000

H

0.65 K

8.6x14 km

6.0x13.4 km

8

89.0

6000

V

0.57 K

4.4x7.2 km

3.0x13.4 km

9

89.0

6000

H

0.57 K

4.4x7.2 km

3.0x13.4 km

10

166.5

4000

V

1.5 K

4.4x7.2 km

3.0x13.4 km

11

166.5

4000

H

1.5 K

4.4x7.2 km

3.0x13.4 km

13

183.31 ± 7

2000

V

1.5 K

4.4x7.2 km

3.0x13.4 km

12

183.31 ± 3

2000

V

1.5 K

4.4x7.2 km

3.0x13.4 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 (near surface)
Secondary mission objectives
  • Cloud liquid water (CLW) total column
  • Integrated Water Vapour (IWV)
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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)2 - very highPoor time sampling.. Time sampling to be interpolated by GEO.MW channels around 10, 19, 23, 37 and 90 GHz, with high spatial resolution
Cloud liquid water (CLW)2 - very highNo specific limitation.MW channels around 37 and 90 GHz, and in 183 GHz band
Cloud liquid water (CLW) total column2 - very highNo specific limitation.MW channels around 37 and 90 GHz, and in 183 GHz band
Land surface temperature5 - marginalCoarse spatial resolution.MW channels around 10 GHz
Long-wave Earth surface emissivity4 - fairLong time series needed.MW channels around 10, 19, 37 and 90 GHz. Emissivity across this MW range inferred by statistical analysis
Precipitation intensity at surface (liquid or solid)2 - very highNo specific limitation.MW channels around 10, 19, 23, 37 and 90 GHz, to cover sea and land, heavy and light precipitation. High spatial resolution consistent with the scale of precipitation
Sea surface temperature5 - marginalWarm temperature only.MW channels around 10 GHz
Sea-ice cover2 - very highNo specific limitation.MW channels around 10, 19, 37 and 90 GHz, with high spatial resolution for accurate contour detection
Sea-ice type4 - fairNo specific limitation.MW channels around 10, 19, 37 and 90 GHz. Type interpreted as age/roughness
Snow cover2 - very highCoarse spatial resolution.MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow . High resolution closer to the scale of snow fields
Snow status (wet/dry)1 - primaryCoarse spatial resolution.MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow. High resolution closer to the scale of snow fields
Snow water equivalent1 - primaryCoarse spatial resolution.. Ground stations network needed.MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow. High resolution closer to the scale of snow fields
Soil moisture at surface3 - highCoarse spatial resolution.. Strongly affected by vegetation.MW channels around 10 GHz
Integrated Water Vapour (IWV)1 - primaryNo specific limitation.MW channel(s) in the water vapour bands around 23 and 183 GHz
Wind speed (near surface)3 - highOver sea only.MW channels around 10, 19 and 37 GHz