BackForwardInstrument:  GAS-2 

Instrument details
Acronym GAS-2
Full name Greenhouse-gases Absorption Spectrometer - 2
Purpose Atmospheric chemistry - Measurement of CO2, CH4, CO, N2O
Short description

Grating spectrometer operating in four NIR/SWIR bands [see detailed characteristics below]
Background

Follow-on of GAS flown on FY-3D
Scanning Technique

Two views, nadir or pointing to sunglint
Resolution 3 km s.s.p.
Coverage / Cycle Global coverage in one month for cells of 100 km side, in daylight. Swath 100 km.
Mass Power Data Rate

 

Providing Agency CMA
Instrument Maturity Flown on operational programme
Utilization Period: 2025 to 2033
Last update: 2025-06-09
Detailed characteristics
Spectral range (μm) Spectral range (cm-1) Spectral resolution SNR @ expected input radiance
0.75-0.77 μm 13000-13300 cm-1 0.04 nm > 300
1.56-1.72 μm 5800-6400 cm-1 0.07 nm > 300
1.92-2.08 μm 4800-5200 cm-1 0.09 nm > 300
2.20-2.38 μm 4200-4550 cm-1 0.10 nm > 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
WIGOS Subcomponents
  • Subcomponent 1
  • UV/VIS/NIR sounders, nadir and limb
  • UV/VIS/NIR nadir sounder
  • Subcomponent 2
  • NIR/SWIR imaging spectroscopy
  • NIR/SWIR imaging spectrometer
  • Subcomponent 3
  • NIR spectrometer
  • NIR spectrometer
Mission objectives
Primary mission objectives
  • CH4 mole fraction
  • CO
  • CO2 mole fraction
  • N2O mole fraction
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
CH4 mole fraction*3 - highCloud sensitive.. Daylight only.. Along-track only.SWIR spectrometry. CH4 lines around 2.3 micrometers
Cloud top height4 - fairDaylight only.. Along-track only.NIR spectrometry to estimate the total-column O2 above the cloud top as measured around 760 nm
CO*3 - highCloud sensitive.. Daylight only.. Along-track only.SWIR spectrometry. CO lines around 2.3 micrometers
CO2 mole fraction*3 - highCloud sensitive.. Daylight only.. Along-track only.SWIR spectroscopy. CO2 lines around 1.6 and 2.1 micrometers
N2O mole fraction*3 - highAlong-track only.. Cloud sensitive.. Daylight only.SWIR spectrometry. N2O lines around 2.3 micrometers