BackForwardInstrument:  AIRS 

Instrument details
Acronym AIRS
Full name Atmospheric Infra-Red Sounder
Purpose Temperature/humidity sounding, ozone profile and total-column green-house gases
Short description Grating spectrometer, 2378 channels, resolving power 1200, 4 supporting channels in VIS/NIR [see detailed characteristics below]
Background New development
Scanning Technique Cross-track: 90 samples scanned, swath 1650 km - Along-track: one 13.5-km line each 2.67 s
Resolution 13.5 km IFOV for the spectrometer; 2.3 km IFOV for VIS/NIR channels
Coverage / Cycle Global coverage once/day
Mass 177 kg Power 220 W Data Rate 1.27 Mbps

 

Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2002-09-01 to ≥2017
Last update: 2012-09-05
Detailed characteristics
Spectral range (µm) Spectral range (cm-1) Spectral resolution SNR or NEΔT @ specified input
3.74 - 4.61 µm 2170 - 2674 cm-1 ~ 2.0 cm-1 0.14 K @ 280 K
6.20 - 8.22 µm 1216 - 1613 cm-1 ~ 1.0 cm-1 0.20 K @ 280 K
8.80 - 15.4 µm 650 - 1136 cm-1 ~ 0.5 cm-1 0.35 K @ 280 K
0.41 - 0.44 µm not relevant 30 nm > 100 @ 40 % albedo
0.58 - 0.68 µm not relevant 100 nm > 100 @ 40 % albedo
0.71 - 0.92 µm not relevant 210 nm > 100 @ 40 % albedo
0.49 - 0.94 µm not relevant N/A (broadband) > 100 @ 40 % albedo
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 optical radiometer or spectrometer
  • Cross-nadir infrared sounder, possibly including VIS channels
Mission objectives
Primary mission objectives
  • Atmospheric temperature
  • Height of the top of PBL
  • Height of the tropopause
  • Integrated Water Vapour (IWV)
  • Specific humidity
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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 temperature2 - very highCloud sensitive.MWIR spectrometry in the CO2 4.3 micrometer band; TIR in the CO2 15 micrometer band
C2H25 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. C2H2 lines around 7.5 and 13.7 micrometers
C2H65 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. C2H6 lines around 12 micrometers
CFC-115 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. CFC-11 lines around 9.2 and 11.7 micrometers
CFC-125 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. CFC-12 lines around 8.8 and 10.8 micrometers
ClONO25 - marginalCloud sensitive.. Coarse vertical resolution.MWIR and TIR spectrometry. ClONO2 lines around 5.7, 7.7 and 12.5 micrometers
Cloud cover2 - very highDiscontinuous coverage.MWIR and TIR spectrometry
Cloud top height1 - primaryDiscontinuous coverage.MWIR and TIR spectrometry in window and water vapour band (for emissivity) to estimate cloud top height from its temperature
Cloud top temperature1 - primaryDiscontinuous coverage.TIR spectrometry in window and water vapour band (for emissivity)
Cloud type3 - highDiscontinuous coverage.MWIR and TIR spectrometry
CO25 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. CO2 lines around 15 micrometers
COS5 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. COS lines around 11.6 micrometers
Downward long-wave irradiance at Earth surface4 - fairCloud sensitive.. Highly indirect.MWIR and TIR spectrometry including water vapour and CO2 bands
H2O5 - marginalCloud sensitive.. Coarse vertical resolution.MWIR/TIR spectrometry in a range centred on 6.3 micrometers
Height of the top of PBL4 - fairCloud sensitive.MWIR and TIR spectrometry. Height of PBL top from temperature profile
Height of the tropopause5 - marginalCloud sensitive.TIR spectrometry. Height of tropopause from temperature profile
HNO35 - marginalCloud sensitive.. Coarse vertical resolution.MWIR and TIR spectrometry. HNO3 lines around 5.9, 7.6 and 11.3 micrometers
Land surface temperature2 - very highCloud sensitive.. Coarse spatial resolution.MWIR and TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections)
Long-wave Earth surface emissivity3 - highCloud sensitive.. Long time series needed.MWIR and TIR spectrometry measuring land temperature in many windows. Emissivity inferred by statistical analysis
NO2 (Total column)5 - marginalCloud sensitive.TIR spectrometry. NO2 lines around 6.1 micrometers
O34 - fairCloud sensitive.. Coarse vertical resolution.TIR spectrometry. Ozone band around 9.7 micrometers
O3 (Total column)4 - fairCloud sensitive.TIR channel(s). Ozone lines in band around 9.7 micrometers
PAN5 - marginalCloud sensitive.. Coarse spatial resolution.MWIR and TIR spectrometry. PAN lines around 5.7, 8.6 and 12.5 micrometers
PSC occurrence4 - fairCoarse vertical resolution.MWIR and TIR spectroscopy
Sea surface temperature1 - primaryCloud sensitive.MWIR and TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections)
SF65 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. SF6 lines around 10.5 micrometers
SO25 - marginalCloud sensitive.. Coarse vertical resolution.TIR spectrometry. SO2 lines around 7.3 and 8.6 micrometers
SO2 (Total column)5 - marginalCloud sensitive.TIR spectrometry. SO2 lines around 7.3 and 8.6 micrometers
Specific humidity2 - very highCloud sensitive.TIR spectrometry in the water vapour band around 6.3 micrometers
Integrated Water Vapour (IWV)2 - very highCloud sensitive.TIR spectrometry in the bands around 6.3 and above 11 micrometers
Temperature of the tropopause4 - fairCloud sensitive.TIR spectrometry. Tropopause temperature from temperature profile
Upward spectral radiance at TOA3 - highMissing all Short-waves.MWIR and TIR spectrometry resolving water vapour lines in the bands around 6.3 micrometers and 11 to 15 micrometers; and other greenhouse gases
Upward long-wave irradiance at TOA2 - very highSpectral interpolation needed.MWIR and TIR spectrometry in the windows regions around 3.7 and 11 micrometers, and in water vapour and CO2 bands around 4,3, 6.3 and 15 micrometers
Upward long-wave irradiance at Earth surface3 - highCloud sensitive.. Highly indirect.MWIR and TIR channels in windows around 3.7 and 11 micrometers, and in water vapour and CO2 bands around 4,3, 6.3 and 15 micrometers