BackForwardInstrument:  GAS 

Instrument details
Acronym GAS
Full name Greenhouse-gases Absorption Spectrometer
Purpose Atmospheric chemistry - Measurement of CO2, CH4, CO, N2O
Short description Grating spectrometer operating in four NIR/SWIR bands [see detailed characteristics below]
Background New development
Scanning Technique Two views, nadir or pointing to sunglint
Resolution 10 km s.s.p.
Coverage / Cycle Global coverage in one month for cells of 100 km side, in daylight
Mass Power Data Rate


Providing Agency CMA
Instrument Maturity Backed by strong heritage
Utilization Period: ≥2017 to ≥2026
Last update: 2016-06-16
Detailed characteristics
Spectral range (μm) Spectral range (cm-1) Spectral resolution SNR @ expected input radiance
0.75-0.77 μm 13000-13300 cm-1 0.60 cm-1 > 300
1.56-1.72 μm 5800-6400 cm-1 0.27 cm-1 > 300
1.92-2.08 μm 4800-5200 cm-1 0.27 cm-1 > 300
2.20-2.38 μm 4200-4550 cm-1 0.27 cm-1 > 300
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 shortwave (UV/VIS) sounder
Mission objectives
Primary mission objectives
  • CH4
  • CO
  • CO2
  • N2O
Opportunity objectives
  • Cloud top height
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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
CH43 - highCloud sensitive.. Daylight only.. Along-track only.SWIR spectrometry. CH4 lines around 2.3 micrometers
Cloud top height5 - marginalDaylight only.. Along-track only.NIR spectrometry to estimate the total-column O2 above the cloud top as measured around 760 nm
CO4 - fairCloud sensitive.. Daylight only.. Along-track only.SWIR spectrometry. CO lines around 2.3 micrometers
CO24 - fairCloud sensitive.. Daylight only.. Along-track only.SWIR spectroscopy. CO2 lines around 1.6 and 2.1 micrometers
N2O3 - highCloud sensitive.. Daylight only.SWIR spectrometry. N2O lines around 2.3 micrometers