BackForwardInstrument:  WiFS 

Instrument details
Acronym WiFS
Full name Wide-Field Sensor
Purpose Land and vegetation observation
Short description Two parallel radiometers, 2 VNIR channels [see detailed characteristics below]
Background Consolidated technology
Scanning Technique Pushbroom, 4000 pixel/line, swath 770 km (with two instruments)
Resolution 190 m at s.s.p.
Coverage / Cycle Global coverage in 5 days, in daylight
Mass 23 kg Power 22 W Data Rate 2.1 Mbps

 

Providing Agency ISRO
Instrument Maturity Backed by strong heritage
Utilization Period: 1996 to 2010-01-15
Last update: 2016-10-20
Detailed characteristics

Central wavelength

Spectral interval

SNR @ specified input spectral radiance

0.650 µm

0.62-0.68 µm

200 @ 263 W m-2 sr-1 µm-1

0.815 µm

0.77-0.86 µm

200 @ 285 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
  • High resolution optical imager
Mission objectives
Primary mission objectives
  • Biomass
  • Fraction of vegetated land
  • Land cover
  • Leaf Area Index (LAI)
  • Normalised Difference Vegetation Index (NDVI)
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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
Biomass5 - marginalCloud sensitive.. Index only.. Infrequent coverage.. Daylight only.VIS and NIR channels. Biomass inferred from NDVI
Cloud cover5 - marginalInfrequent coverage.. Daylight only.VIS and NIR channels
Cloud optical depth5 - marginalLow-density cloud only.. Infrequent coverage.. Daylight only.VIS and NIR channels
Fraction of vegetated land2 - very highCloud sensitive.. Daylight only.VIS and NIR channels
Glacier cover5 - marginalCloud sensitive.. Long time for mapping.. Daylight only.VIS and NIR channels
Glacier topography5 - marginalCloud sensitive.. Long time for mapping.. Daylight only.VIS channel(s) and cross-track steering capability for stereoscopy between images from neighbour orbits
Ice sheet topography5 - marginalCloud sensitive.. Long time for mapping.. Daylight only.VIS channel(s) and cross-track steering capability for stereoscopy between images from neighbour orbits
Land cover3 - highCloud sensitive.. Daylight only.VIS and NIR channels
Land surface topography5 - marginalCloud sensitive.. Long time for mapping.. Daylight only.VIS channel(s) and cross-track steering capability for stereoscopy between images from neighbouring orbits
Leaf Area Index (LAI)5 - marginalCloud sensitive.. Daylight only.. Infrequent coverage.VIS and NIR channels. LAI inferred from NDVI
Normalised Difference Vegetation Index (NDVI)2 - very highCloud sensitive.. Infrequent coverage.VIS and NIR channels
Sea-ice cover5 - marginalCloud sensitive.. Daylight only.VIS and NIR (for contour enhancement) channels
Short-wave cloud reflectance5 - marginalInfrequent coverage.VIS and NIR channels. Unsuitable dynamic range (saturation)
Snow cover5 - marginalCloud sensitive.. Infrequent coverage.. Daylight only.VIS and NIR channels
Soil moisture at surface5 - marginalCloud sensitive.. Index only.. Infrequent coverage.. Daylight only.VIS and NIR channels. Soil moisture inferred from differential brightness
Soil type5 - marginalCloud sensitive.. Daylight only.VIS and NIR channels
Upward short-wave irradiance at TOA5 - marginalSpectral interpolation needed.. Information on BRDF needed.. Infrequent coverage.VIS and NIR channels
Vegetation type4 - fairCloud sensitive.. Daylight only.VIS and NIR channels
Aerosol volcanic ash5 - marginalCloud sensitive.. Infrequent coverage.. Daylight only.VIS and NIR channels
Aerosol volcanic ash (Total column)5 - marginalCloud sensitive.. Infrequent coverage.. Daylight only.VIS and NIR channels