BackForwardInstrument:  AMSU-A 

Instrument details
Acronym AMSU-A
Full name Advanced Microwave Sounding Unit - A
Purpose Temperature sounding in nearly-all-weather conditions
Short description 15 channels including the 54 GHz band [see detailed characteristics below]
Background Replacing MSU flown on TIROS-N and NOAA-9 to -14. Operations on NOAA-17 stopped in 2003. AMSU-A is part of the ATOVS sounding instrument suite (Advanced TIROS Operational Vertical Sounder)
Scanning Technique Cross-track: 30 steps of 48 km s.s.p., swath 2250 km - Along-track: one 48-km line every 8 s
Resolution 48 km IFOV
Coverage / Cycle Near-global coverage twice/day
Mass 104 kg Power 99 W Data Rate 3.2 kbps

 

Providing Agency NOAA
Instrument Maturity Flown on operational programme
Utilization Period: 1998-08-15 to 2003
Last update: 2021-11-03
Detailed characteristics
No. Central frequency (GHz) Bandwidth (MHz) Polarisation NEΔT
1 23.800 270 V 0.30 K
2 31.400 180 V 0.30 K
3 50.300 180 V 0.40 K
4 52.800 400 V 0.25 K
5 53.596 ± 0.115 170 H 0.25 K
6 54.400 400 H 0.25 K
7 54.940 400 V 0.25 K
8 55.500 330 H 0.25 K
9 f0 = 57.290344 330 H 0.25 K
10 f0 ± 0.217 78 H 0.40 K
11 f0 ± 0.3222  ± 0.048 36 H 0.40 K
12 f0 ± 0.3222  ± 0.022 16 H 0.60 K
13 f0 ± 0.3222  ± 0.010 8 H 0.80 K
14 f0 ± 0.3222  ± 0.0045 3 H 1.20 K
15 89.000 6000 V 0.50 K
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
  • Cross-track, special or non-scanning microwave radiometer
WIGOS Subcomponents
  • Subcomponent 1
  • MW sounder [in SSO]
  • MW cross-track upper stratospheric and mesospheric sounder
Mission objectives
Primary mission objectives
  • Atmospheric temperature
Secondary mission objectives
  • Cloud ice Total Column
  • Cloud liquid water (CLW) total column
  • Freezing level height in clouds
  • 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
Atmospheric temperature1 - primaryCoarse vertical resolution.Many MW channels in the 54 GHz band. Nearly all-weather sounding
Cloud ice3 - highNo specific limitation.MW channels around 37 and 90 GHz, and in 54 GHz band
Cloud ice Total Column3 - highNo specific limitation.MW channels around 37 and 90 GHz, and in 54 GHz band
Cloud ice effective radius2 - very highNo specific limitation.MW channels around 37 and 90 GHz, and in 54 GHz band
Cloud liquid water (CLW)2 - very highNo specific limitation.MW channels around 37 and 90 GHz, and in 54 GHz band
Cloud liquid water (CLW) total column2 - very highNo specific limitation.MW channels around 37 and 90 GHz, and in 54 GHz band
Downward long-wave irradiance at Earth surface5 - marginalHighly indirect.MW channels in bands 54 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
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)5 - marginalNo specific limitation.MW channels in the 54 GHz band. Suitable for liquid precipitation over sea and land, Insensitive to surface emissivity
Integrated Water Vapour (IWV)3 - highOver sea only.MW channel(s) in the water vapour band around 23 GHz
Upward long-wave irradiance at Earth surface5 - marginalHighly indirect.MW channels is the 54 GHz band to infer the impact of clouds on the upward LW radiation
Cloud drop effective radius5 - marginalHighly indirect.MW channels around 37 and 90 GHz, and in 54 GHz band