BackForwardInstrument:  Polarimeters 

Instrument details
Acronym Polarimeters
Full name Polarimeters
Purpose Aerosol, cirrus clouds, Bidirectional Reflectance Distribution Function (BRDF)
Short description 12 wavelengths with 3 polarisations at 9 wavelengths - total: 30 channels [see detailed characteristics below]. WARNING: the specs quoted below are being revised. There will probably be two polarimeters, Spectro-Polarimeter for Planetary Exploration (SPEXone), and Hyper Angular Rainbow Polarimeter (HARP-2)
Background Assumed to be the same as 3MI on MetOp-SG-A
Scanning Technique … x … CCD arrays, 2400 km swath, each earth’s spot viewed from ~ 14 directions as satellite moves
Resolution 4 km IFOV
Coverage / Cycle Near-global coverage every day in daylight.
Mass 40 kg Power 60 W Data Rate ~ 4 Mbps

 

Providing Agency CNES
Instrument Maturity Demonstrated by simulations
Utilization Period: TBD
Last update: 2018-06-20
Detailed characteristics
Central wavelength Bandwidth Polarisations SNR @ specified input spectral radiance
410 nm 20 nm three 100 @ 35.5 W m-2 sr-1 µm-1
443 nm 20 nm three 100 @ 48.9 W m-2 sr-1 µm-1
490 nm 20 nm three 100 @ 55.6 W m-2 sr-1 µm-1
555 nm 20 nm three 100 @ 55.2 W m-2 sr-1 µm-1
670 nm 20 nm three 100 @ 44.1 W m-2 sr-1 µm-1
754 nm 20 nm - 200 @ 36.1 W m-2 sr-1 µm-1
763 nm 10 nm - 200 @ 36.0 W m-2 sr-1 µm-1
865 nm 40 nm three 100 @ 28.2 W m-2 sr-1 µm-1
910 nm 20 nm - 200 @ 25.2 W m-2 sr-1 µm-1
1,370 nm 40 nm three 100 @ 10.7 W m-2 sr-1 µm-1
1,650 nm 40 nm three 100 @ 6.8 W m-2 sr-1 µm-1
2,130 nm 40 nm three 100 @ 2.9 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
  • Moderate resolution optical imager
Mission objectives
Primary mission objectives
  • Aerosol Optical Depth
  • Aerosol column burden
  • Aerosol effective radius
  • Aerosol mass mixing ratio
  • Aerosol type
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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 burden1 - primaryCloud sensitive.. Daylight only.VIS (with narrow bandwidth), NIR and SWIR channels including 760 nm, with multi-angle viewing and polarimetry for more aerosol types, also over land
Aerosol effective radius1 - primaryCloud sensitive.. Daylight only.VIS (with narrow bandwidth), NIR and SWIR channels including 760 nm for high-level aerosol, with multi-angle viewing and polarimetry for several aerosol types, also over land
Aerosol mass mixing ratio1 - primaryCloud sensitive.. Daylight only.VIS (with narrow bandwidth), NIR (including 760 nm for high-level aerosol) and SWIR channels, with multi-angle viewing and polarimetry for several aerosol types, also over land
Aerosol Optical Depth1 - primaryCloud sensitive.. Daylight only.VIS (with narrow bandwidth), NIR and SWIR channels including 760 nm for high-level aerosol, with multi-angle viewing and polarimetry for more aerosol types, also over land
Aerosol type1 - primaryCloud sensitive.. Daylight only.VIS (with narrow bandwidth), NIR and SWIR channels including 760 nm for high-level aerosol, with multi-angle viewing and polarimetry for more aerosol types, also over land
Biomass4 - fairCloud sensitive.. Index only.. Daylight only.VIS, NIR and SWIR channels. Biomass inferred from NDVI and LAI
Cloud cover5 - marginalDaylight only.VIS and NIR channels
Cloud drop effective radius4 - fairAt cloud top.. Daylight only.VIS, NIR and SWIR channels and different viewing angles (for differentiation).
Cloud ice effective radius4 - fairAt cloud top.. Daylight only.VIS, NIR and SWIR channels with different viewing angles (for differentiation).
Cloud optical depth2 - very highLow-density cloud only.. Daylight only.VIS, NIR and SWIR channels with different viewing angles
Cloud top height5 - marginalDaylight only.NIR channels to estimate the total-column O2 above the cloud top as measured around 760 nm
Cloud type5 - marginalDaylight only.VIS, NIR and SWIR channels viewing under more angles
Colour Dissolved Organic Matter (CDOM)5 - marginalCloud sensitive.. Daylight only.A few narrow-bandwidth VIS channels, suitable for a few water types, mainly in open ocean
Downward short-wave irradiance at Earth surface3 - highCloud sensitive.. Highly indirect.VIS, NIR and SWIR channels
Earth surface albedo1 - primaryCloud sensitive.VIS channels with many viewing angles to account for anisotropic reflectivity
Earth surface short-wave bidirectional reflectance1 - primaryCloud sensitive.VIS, NIR and SWIR range with many different viewing angles
Fire fractional cover5 - marginalCloud sensitive.. Coarse spatial resolution.. Daylight only.VIS channels
Fraction of Absorbed PAR (FAPAR)1 - primaryCloud sensitive.VIS channels including Red at 700 nm, with more viewing angles
Leaf Area Index (LAI)2 - very highCloud sensitive.. Daylight only.VIS, NIR and SWIR channels
Normalised Difference Vegetation Index (NDVI)3 - highCloud sensitive.VIS and NIR channels
Ocean chlorophyll concentration 5 - marginalCloud sensitive.. Daylight only.A few narrow-bandwidth VIS channels, suitable for a few water types, mainly in open ocean
Ocean Diffuse Attenuation Coefficient (DAC)5 - marginalCloud sensitive.. Daylight only.A few narrow-bandwidth VIS channels, suitable for a few water types, mainly in open ocean
Ocean suspended sediments concentration5 - marginalCloud sensitive.. Daylight only.A few narrow-bandwidth VIS channels, suitable for a few water types, mainly in open ocean
Oil spill cover3 - highCloud sensitive.. Daylight only.VIS channels with narrow bandwidth, with different viewing angles
Photosynthetically Active Radiation (PAR)1 - primaryCloud sensitive.VIS channels, range undersampled; multi-viewing capability for irradiance reconstruction
Sea-ice cover4 - fairCloud sensitive.. Daylight only.VIS, NIR (for contour enhancement) and SWIR (for discrimination from clouds) channels
Short-wave cloud reflectance1 - primaryNo specific limitation.VIS, NIR and SWIR channels with multi-viewing and multi-polarisation capabiliy to account for anisotropical reflectance
Snow cover2 - very highCloud sensitive.. Daylight only.VIS, NIR and SWIR channels, enabling screening snow from clouds
Soil moisture at surface5 - marginalCloud sensitive.. Index only.. Daylight only.VIS, NIR and SWIR channels. Soil moisture inferred from differential brightness
Integrated Water Vapour (IWV)5 - marginalCloud sensitive.. Daylight only.NIR channels in the ro-sigma-tau band of water vapour around 940 nm
Upward short-wave irradiance at TOA4 - fairSpectral interpolation needed.VIS, NIR and SWIR channels with multi-viewing and multi-polarisation capability to account for anisotropical reflectance
Aerosol volcanic ash1 - primaryCloud sensitive.. Daylight only.VIS, NIR and SWIR channels including 760 nm, with multi-angle viewing and polarimetry for accurate ash identification, also over land
Aerosol volcanic ash Total Column1 - primaryCloud sensitive.. Daylight only.VIS, NIR and SWIR channels including 760 nm, with multi-angle viewing and polarimetry for accurate ash identification, also over land