BackForwardInstrument:  APS 

Instrument details
Acronym APS
Full name Aerosol Polarimetry Sensor
Purpose Aerosol optical thickness, size distribution and shape
Short description 9-channel VIS/NIR/SWIR polarimeter with multi-angle capability [see detailed characteristics below]
Background Failed with Glory at launch
Scanning Technique Along-track viewing only, fore- and aft- ± 60° (250 steps of 8 mrad), one full measurement every ~ 10 km
Resolution 5.6 km
Coverage / Cycle ~ 30000 measurements/day at ~ 10 km intervals - Global coverage (25 km average spacing) in 30 days
Mass 69 kg Power 55 W Data Rate 160 kbps

 

Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2011-03-04 to 2011-03-04
Last update: 2017-03-26
Detailed characteristics
Central λ Bandwidth Polarisations SNR @ specified input spectral radiance
412 nm 20 nm 0, 45, 90 and 135 degrees 235 @ ….. W m-2 sr-1 μm-1
443 nm 20 nm 0, 45, 90 and 135 degrees 235 @ ….. W m-2 sr-1 μm-1
555 nm 20 nm 0, 45, 90 and 135 degrees 235 @ ….. W m-2 sr-1 μm-1
672 nm 20 nm 0, 45, 90 and 135 degrees 235 @ ….. W m-2 sr-1 μm-1
865 nm 39 nm 0, 45, 90 and 135 degrees 235 @ ….. W m-2 sr-1 μm-1
910 nm 20 nm 0, 45, 90 and 135 degrees  94 @ ….. W m-2 sr-1 μm-1
1378 nm 35 nm 0, 45, 90 and 135 degrees 141 @ ….. W m-2 sr-1 μm-1
1610 nm 60 nm 0, 45, 90 and 135 degrees 235 @ ….. W m-2 sr-1 μm-1
2250 nm 75 nm 0, 45, 90 and 135 degrees 235 @ ….. 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 volcanic ash
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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 burden3 - highCloud sensitive.. Daylight only.. Along-track only.VIS (with narrow bandwidth), NIR and SWIR channels, multi-angle viewing and polarimetry for several aerosol types, also over land
Aerosol effective radius5 - marginalCloud sensitive.. Daylight only.. Along-track only.VIS (with narrow bandwidth), NIR and SWIR channels viewing under different angles
Aerosol mass mixing ratio5 - marginalCloud sensitive.. Daylight only.. Along-track only.VIS (with narrow bandwidth), NIR and SWIR channels, multi-angle viewing and polarimetry for several aerosol types, also over land
Aerosol Optical Depth3 - highCloud sensitive.. Daylight only.. Along-track only.VIS (with narrow bandwidth), NIR and SWIR channels, multi-angle viewing and polarimetry for several aerosol types, also over land
Biomass5 - marginalCloud sensitive.. Index only.. Along-track only.. Daylight only.VIS, NIR and SWIR channels. Biomass inferred from NDVI and LAI
Cloud cover5 - marginalDaylight only.. Along-track only.VIS and NIR channels
Cloud drop effective radius4 - fairAt cloud top.. Daylight only.. Along-track only.VIS, NIR and SWIR channels and different viewing angles (for differentiation).
Cloud ice effective radius4 - fairAt cloud top.. Daylight only.. Along-track only.VIS, NIR and SWIR channels with different viewing angles (for differentiation).
Cloud optical depth3 - highLow-density cloud only.. Daylight only.. Along-track only.VIS, NIR and SWIR channels with different viewing angles
Cloud type4 - fairDaylight only.. Along-track only.VIS, NIR and SWIR channels viewing under more angles
Colour Dissolved Organic Matter (CDOM)5 - marginalCloud sensitive.. Daylight only.. Along-track only.A few narrow-bandwidth VIS channels, suitable for a few water types, mainly in open ocean
Downward short-wave irradiance at Earth surface5 - marginalCloud sensitive.. Highly indirect.. Along-track only.VIS, NIR and SWIR channels
Earth surface albedo2 - very highCloud sensitive.. Along-track only.VIS channels with many viewing angles to account for anisotropic reflectivity
Earth surface short-wave bidirectional reflectance4 - fairCloud sensitive.. Along-track only.VIS, NIR and SWIR channels with a few different viewing angles
Fire fractional cover5 - marginalCloud sensitive.. Coarse spatial resolution.. Daylight only.. Along-track only.VIS channels
Fraction of Absorbed PAR (FAPAR)2 - very highCloud sensitive.. Along-track only.VIS channels including Red at 700 nm, with more viewing angles
Leaf Area Index (LAI)3 - highCloud sensitive.. Daylight only.. Along-track only.VIS, NIR and SWIR channels
Normalised Difference Vegetation Index (NDVI)3 - highCloud sensitive.. Along-track only.VIS and NIR channels
Ocean chlorophyll concentration 5 - marginalCloud sensitive.. Daylight only.. Along-track 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.. Along-track 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.. Along-track only.A few narrow-bandwidth VIS channels, suitable for a few water types, mainly in open ocean
Oil spill cover3 - highCloud sensitive.. Daylight only.. Along-track only.VIS channels with narrow bandwidth, with different viewing angles
Photosynthetically Active Radiation (PAR)2 - very highCloud sensitive.. Along-track only.VIS channels, range undersampled; multi-viewing capability for irradiance reconstruction
Sea-ice cover5 - marginalCloud sensitive.. Daylight only.. Along-track only.VIS, NIR (for contour enhancement) and SWIR (for discrimination from clouds) channels
Short-wave cloud reflectance1 - primaryAlong-track only.VIS, NIR and SWIR channels with multi-viewing and multi-polarisation capabiliy to account for anisotropical reflectance
Snow cover3 - highCloud sensitive.. Daylight only.. Along-track only.VIS, NIR and SWIR channels, enabling screening snow from clouds
Soil moisture at surface5 - marginalCloud sensitive.. Index only.. Daylight only.. Along-track only.VIS, NIR and SWIR channels. Soil moisture inferred from differential brightness
Integrated Water Vapour (IWV)5 - marginalCloud sensitive.. Daylight only.. Along-track only.NIR channels in the ro-sigma-tau band of water vapour around 940 nm
Upward short-wave irradiance at TOA4 - fairSpectral interpolation needed.. Along-track only.VIS, NIR and SWIR channels with multi-viewing and multi-polarisation capability to account for anisotropical reflectance
Aerosol volcanic ash4 - fairCloud sensitive.. Daylight only.. Along-track only.VIS, NIR and SWIR channels, multi-angle viewing and polarimetry for accurate ash identification, also over land
Aerosol volcanic ash (Total column)3 - highCloud sensitive.. Daylight only.. Along-track only.VIS, NIR and SWIR channels, multi-angle viewing and polarimetry for accurate ash identification, also over land