BackForwardInstrument:  ACS-nadir 

Instrument details
Acronym ACS-nadir
Full name Atmospheric Composition Spectrometer (nadir-scanning component)
Purpose Atmospheric chemistry. Tracked species: BrO, CH4, ClO, CO, CO2, H2O, HCHO, N2O, NO, NO2, NO3, O2, O3, O4, OClO, SO2 and aerosol.
Short description UV/VIS/NIR/SWIR grating spectrometer, eight bands, 2048 channels [see detailed characteristics below]
Background New development
Scanning Technique Cross-track, swath 1000 km - The cross-nadir mode is alternative to the limb mode and the solar/lunar occultation mode.
Resolution 8-14 km at s.s.p.
Coverage / Cycle Global in 3 days.
Mass Power Data Rate

 

Providing Agency Roscosmos
Instrument Maturity Backed by strong heritage
Utilization Period: ≥2025 to ≥2033
Last update: 2018-02-06
Detailed characteristics

Spectral range

No. of channels

Spectral resolution

SNR @ specified input spectral radiance

214-334 nm

256

0.5 nm

..... @ ...... W m-2 sr-1 μm-1

320-452 nm

256

0.5 nm

..... @ ...... W m-2 sr-1 μm-1

430-800 nm

256

1.5 nm

..... @ ...... W m-2 sr-1 μm-1

755-910 nm

256

0.9 nm

..... @ ...... W m-2 sr-1 μm-1

900-1210 nm

256

0.9 nm

..... @ ...... W m-2 sr-1 μm-1

1200-1770 nm

256

2.0 nm

..... @ ...... W m-2 sr-1 μm-1

1934-2044 nm

256

0.5 nm

..... @ ...... W m-2 sr-1 μm-1

2259-2386 nm

256

0.5 nm

..... @ ...... W m-2 sr-1 μm-1

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
  • BrO Mole Fraction
  • CH4 Mole Fraction
  • CO Mole Fraction
  • CO2 Mole Fraction
  • ClO Mole Fraction
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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
Aerosol column burden2 - very highCloud sensitive.. Daylight only.UV (for absorbing aerosol), VIS, NIR and SWIR spectrometry including the 760 nm band for high-level aerosol
Aerosol effective radius2 - very highCloud sensitive.. Daylight only.UV, VIS, NIR (including the 760 nm band for high-level aerosol) and SWIR spectrometry
Aerosol mass mixing ratio2 - very highCloud sensitive.. Daylight only.UV (for absorbing aerosol), VIS, NIR (including the 760 nm band for high-level aerosol) and SWIR spectrometry
Aerosol Optical Depth2 - very highCloud sensitive.. Daylight only.UV, VIS, NIR and SWIR spectrometry including the 760 nm band for high-level aerosol
Aerosol type2 - very highCloud sensitive.. Daylight only.UV (for absorbing aerosol), VIS, NIR and SWIR spectrometry including the 760 nm band for high-level aerosol
BrO Mole Fraction1 - primaryCloud sensitive.. Daylight only.UV spectrometry. BrO lines around 300 nm
HCHO Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.. Daylight only.UV spectrometry. HCHO lines around 350 nm
HCHO Total Column2 - very highCloud sensitive.. Daylight only.UV spectrometry. HCHO lines around 350 nm
CH4 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.. Daylight only.SWIR spectrometry. CH4 lines around 2.3 micrometers
ClO Mole Fraction1 - primaryCloud sensitive.. Daylight only.UV Spectrometry. ClO lines around 300 nm
Cloud cover4 - fairDaylight only.VIS, NIR and SWIR spectroscopy
Cloud drop effective radius4 - fairAt cloud top.. Daylight only.VIS, NIR and SWIR spectrometry
Cloud ice effective radius4 - fairAt cloud top.. Daylight only.VIS, NIR and SWIR spectrometry
Cloud optical depth2 - very highLow-density cloud only.. Daylight only.VIS, NIR and SWIR spectrometry
Cloud top height4 - fairDaylight only.NIR spectrometry to estimate the total-column O2 above the cloud top as measured around 760 nm
CO Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.. Daylight only.SWIR spectrometry. CO lines around 2.3 micrometers
CO2 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.. Daylight only.SWIR spectrometry. CO2 lines around 1.6 and 2.1 micrometers
Downward short-wave irradiance at Earth surface1 - primaryCloud sensitive.. Highly indirect.. Daylight only.VIS, NIR and SWIR spectrometry
Earth surface albedo4 - fairCloud sensitive.VIS spectrometry, range fully covered
Fraction of Absorbed PAR (FAPAR)2 - very highCloud sensitive.VIS spectrometry including Red at 700 nm
H2O Mole Fraction3 - highCloud sensitive.. Daylight only.Spectrometry in UV and VIS (several weak bands), and NIR and SWIR (strong bands around 940 nm and 1380 nm)
N2O Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.. Daylight only.SWIR spectrometry. N2O lines around 2.3 micrometers
NO Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.. Daylight only.UV spectrometry. NO lines around 250 nm
NO2 Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.. Daylight only.UV and VIS spectrometry. Several lines in the ranges around 220 nm and 400 nm
NO2 Total Column2 - very highCloud sensitive.. Daylight only.UV and VIS spectrometry. Several NO2 lines
O3 Mole Fraction2 - very highCloud sensitive.. Daylight only.UV and VIS spectrometry. Ozone lines in the bands around 260 nm (Hartley) and/or 340 nm (Huggins) and 600 nm (Chappuis)
O3 Total Column2 - very highCloud sensitive.. Daylight only.UV and VIS spectrometry. Ozone lines in the bands around 260 nm (Hartley) and/or 340 nm (Huggins) and 600 nm (Chappuis)
Photosynthetically Active Radiation (PAR)2 - very highCloud sensitive.VIS spectrometry, range fully covered
PSC occurrence2 - very highCoarse vertical resolution.. Daylight only.UV and VIS spectrometry
Short-wave cloud reflectance3 - highNo specific limitation.VIS, NIR and SWIR spectrometry. Unsuitable dynamic range (saturation)
SO2 Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.. Daylight only.UV spectrometry. SO2 lines around 350 nm
SO2 Total Column3 - highCloud sensitive.. Daylight only.UV spectrometry. SO2 lines around 350 nm
Specific humidity4 - fairCloud sensitive.. Very coarse vertical resolution.. Daylight only.NIR spectrometry including the ro-sigma-tau band of water vapour around 940 nm
Integrated Water Vapour (IWV)5 - marginalCloud sensitive.. Daylight only.NIR spectrometry covering the 940 nm band
Upward short-wave irradiance at TOA3 - highInformation on BRDF needed.UV, VIS, NIR and SWIR spectrometry
Upward spectral radiance at TOA4 - fairMissing all Long-waves.UV, VIS, NIR and SWIR spectrometry
Aerosol volcanic ash2 - very highCloud sensitive.. Daylight only.UV (specifically sensitive to ash), VIS, NIR and SWIR spectrometry including the 760 nm band for high-level ash
Aerosol volcanic ash Total Column2 - very highCloud sensitive.. Daylight only.UV (specifically sensitive to ash), VIS, NIR and SWIR spectrometry including the 760 nm band for high-level ashl