BackForwardInstrument:  VIRR (FY-3) 

Instrument details
Acronym VIRR (FY-3)
Full name Visible and Infra-Red Radiometer
Purpose Multi-purpose imagery with emphasis on vegetation and ocean colour
Short description 10 VIS/NIR/SWIR/MWIR/TIR channels [see detailed characteristics below]
Background Similar to MVISR on FY 1C and 1D
Scanning Technique Cross-track: 2048 pixel of 800 m s.s.p., swath 2800 km - Along-track: six 1.1-km lines/s
Resolution 1.1 km at s.s.p.
Coverage / Cycle Global coverage twice/day (IR) or once/day (VIS)
Mass 55 kg Power 45 W Data Rate 1.23 Mbps

 

Providing Agency CMA
Instrument Maturity Flown on operational programme
Utilization Period: 2008 to ≥2020
Last update: 2017-03-27
Detailed characteristics
Central wavelength Spectral interval SNR or NEΔT @ specified input
0.455 µm 0.43 - 0.48 µm 3.0 @ 0.5 % albedo
0.505 µm 0.48 - 0.53 µm 3.0 @ 0.5 % albedo
0.555 µm 0.53 - 0.58 µm 3.0 @ 0.5 % albedo
0.630 µm 0.58 - 0.68 µm 3.0 @ 0.5 % albedo
0.865 µm 0.84 – 0.89 µm 3.0 @ 0.5 % albedo
1.360 µm 1.325 - 1.395 µm 3.0 @ 0.5 % albedo
1.600 µm 1.55 - 1.64 µm 3.0 @ 0.5 % albedo
3.740 µm 3.55 - 3.93 µm 0.40 K @ 300 K
10.80 µm 10.3 - 11.3 µm  0.2 K @ 300 K
12.00 µm 11.5 - 12.5 µm  0.2 K @ 300 K
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
  • Cloud cover
  • Cloud optical depth
  • Cloud top height
  • Cloud top temperature
  • Cloud 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
Biomass4 - fairCloud sensitive.. Index only.. Daylight only.VIS, NIR and SWIR channels. Biomass inferred from NDVI and LAI
Cloud cover1 - primaryNo specific limitation.VIS, NIR, SWIR, MWIR and TIR channels
Cloud drop effective radius3 - highAt cloud top.. Daylight only.VIS, NIR, SWIR and MWIR channels (for differentiation)
Cloud ice effective radius3 - highAt cloud top.. Daylight only.VIS, NIR, SWIR and MWIR channels (for differentiation)
Cloud optical depth3 - highLow-density cloud only.. Daylight only.VIS, NIR and SWIR channels
Cloud top height4 - fairNo specific limitation.TIR window channels to estimate cloud top height from its temperature
Cloud top temperature4 - fairNo specific limitation.TIR window channels
Cloud type1 - primaryNo specific limitation.VIS, NIR, SWIR, MWIR and TIR channels
Downward short-wave irradiance at Earth surface3 - highCloud sensitive.. Highly indirect.VIS, NIR and SWIR channels
Earth surface albedo5 - marginalCloud sensitive.VIS channels
Fire fractional cover4 - fairCloud sensitive.. Coarse spatial resolution.VIS, MWIR and TIR channels
Fire radiative power2 - very highCloud sensitive.. Coarse spatial resolution.MWIR and TIR channels
Fire temperature2 - very highCloud sensitive.. Coarse spatial resolution.MWIR and TIR channels
Fraction of Absorbed PAR (FAPAR)4 - fairCloud sensitive.VIS channels including Red at 700 nm
Land surface temperature3 - highCloud sensitive.MWIR and TIR window channels (high sensitivity to high temperature, cloud impact reduction, water vapour correction)
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
Photosynthetically Active Radiation (PAR)4 - fairCloud sensitive.VIS channels, range undersampled
Sea surface temperature2 - very highCloud sensitive.MWIR and TIR window channels around 3.7 and 11 micrometers (cloud impact reduction, water vapour correction)
Sea-ice cover1 - primaryCloud sensitive.VIS, NIR (for contour enhancement), SWIR (for discrimination from clouds), MWIR and TIR channels
Short-wave cloud reflectance4 - fairNo specific limitation.VIS, NIR and SWIR channels
Snow cover2 - very highCloud sensitive.. Daylight only.VIS, NIR and SWIR channels, enabling screening snow from clouds
Soil moisture at surface4 - fairCloud sensitive.. Index only.VIS, SWIR, MWIR and TIR channels. Soil moisture inferred from differential brightness and thermal inertia
Integrated Water Vapour (IWV)3 - highCloud sensitive.. Low troposphere dominant.NIR and TIR channels around 940 nm and in the 11 micrometer split window
Upward short-wave irradiance at TOA5 - marginalSpectral interpolation needed.. Information on BRDF needed.VIS, NIR and SWIR channels
Aerosol volcanic ash5 - marginalCloud sensitive.. Daylight only.VIS, NIR and SWIR channels
Aerosol volcanic ash Total Column5 - marginalCloud sensitive.. Daylight only.VIS, NIR and SWIR channels
Wind (horizontal)5 - marginalLimited to high latitudes.. Cloud or water vapour tracers needed.TIR channel(s) around 11 micrometers window