BackForwardInstrument:  VIRS 

Instrument details
Acronym VIRS
Full name Visible and Infra Red Scanner
Purpose Multipurpose VIS/IR imagery
Short description 5 VIS/IR channels [see detailed characteristics below]
Background Adapted from AVHRR/3 (NIR channel missing)
Scanning Technique Cross-track: 256 pixel of 1.6 km s.s.p., swath 720 km - Along-track: 240 lines/min, 1.7 km/scan
Resolution 2.0 km at s.s.p.
Coverage / Cycle Intertropical coverage: several sequences of passes at ~ 100-min intervals with longer gaps once or twice per day. More regular coverage at 15°N and 15°S)
Mass 34.5 kg Power 40 W Data Rate 50 kbps

 

Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 1998 to 2015
Last update: 2022-08-08
Detailed characteristics
Central wavelength Spectral interval SNR or NEΔT @ specified input
0.630 µm 0.58 - 0.68 µm 9 @ 0.5 % albedo
1.61 µm 1.58 - 1.64 µm 20 @ 0.5 % albedo
3.74 µm 3.55 - 3.93 µm 0.12 K @ 300 K
10.80 µm 10.3 - 11.3 µm 0.12 K @ 300 K
12.00 µm 11.5 - 12.5 µm 0.12 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
WIGOS Subcomponents No WIGOS subcomponents have been defined.
Mission objectives
Primary mission objectives
  • Cloud cover
  • Cloud top height
  • Cloud top temperature
  • Cloud type
  • Sea surface temperature
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
Note: * Primary mission objective.
VariableRelevance for measuring this variableOperational limitationsExplanation
Cloud cover*2 - very highNo specific limitation.VIS, SWIR, MWIR and TIR channels
Cloud drop effective radius3 - highAt cloud top.. Daylight only.VIS, SWIR and MWIR channels (for differentiation)
Cloud ice effective radius3 - highAt cloud top.. Daylight only.VIS, SWIR and MWIR channels (for differentiation)
Cloud top height*4 - fairNo specific limitation.TIR window channels to estimate cloud top height from its temperature
Cloud top temperature*4 - fairNo specific limitation.TIR window channels
Cloud type*2 - very highNo specific limitation.VIS, SWIR, MWIR and TIR 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
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)3 - highCloud sensitive.. Daylight only.VIS and SWIR channels
Sea surface temperature*2 - very highCloud sensitive.MWIR and TIR window channels around 3.7 and 11 micrometers (cloud impact reduction, water vapour correction)
Snow cover2 - very highCloud sensitive.. Daylight only.VIS 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)4 - fairCloud sensitive.. Low troposphere dominant.TIR channels in the 11 micrometers split window
Aerosol volcanic ash5 - marginalCloud sensitive.. Daylight only.VIS and SWIR channels
Aerosol volcanic ash Total Column5 - marginalCloud sensitive.. Daylight only.VIS and SWIR channels