BackForwardInstrument:  VHRR (INSAT) 

Instrument details
Acronym VHRR (INSAT)
Full name Very High Resolution Radiometer
Purpose Multi-purpose imagery and wind derivation by tracking clouds and water vapour features
Short description 3 VIS/TIR channels [see detailed characteristics below]
Background Heritage of VHRR flown on ATS-6
Scanning Technique Mechanical, 3-axis stabilised satellite, E-W continuous, S-N stepping
Resolution 8.0 km for IR channels; 2 km for the VIS channel
Coverage / Cycle Full disk every 3 hours for INSAT-2E, 1 hour for INSAT-3A (with half-hourly triplets around 00 and 12 UT for winds), half-hour for Kalpana-1
Mass 60 kg Power 37 W Data Rate 530 kbps

 

Providing Agency ISRO
Instrument Maturity Flown on operational programme
Utilization Period: 1982 to 2017
Last update: 2017-03-27
Detailed characteristics
Central wavelength Spectral interval SNR or NEΔT @ specified input
0.65 µm 0.55 - 0.75 µm 6 @ 2.5 % albedo
6.40 µm 5.70 - 7.10 µm 0.5 K @ 300 K
11.5 µm 10.5 - 12.5 µm 0.25 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 top height
  • Cloud top temperature
  • Cloud type
  • Integrated Water Vapour (IWV)
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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
Accumulated precipitation (over 24 h)3 - highConvective precipitation dominant.. Calibration by MW needed.TIR channel(s) in the 10-13 micrometers range. Frequent sampling (GEO) is essential for accumulated precipitation
Cloud cover4 - fairNo specific limitation.VIS and TIR channels
Cloud top height3 - highNo specific limitation.TIR channels in window and water vapour band (for emissivity) to estimate cloud top height from its temperature
Cloud top temperature3 - highNo specific limitation.TIR channels in window and water vapour band (for emissivity)
Cloud type4 - fairDaylight only.VIS and TIR channels
Fire fractional cover4 - fairCloud sensitive.. Coarse spatial resolution.VIS and TIR channels
Fire radiative power5 - marginalCloud sensitive.. Coarse spatial resolution.TIR channels. Frequent sampling (GEO) enables early detection
Fire temperature5 - marginalCloud sensitive.. Coarse spatial resolution.TIR channels. Frequent sampling (GEO) enables early detection
Precipitation intensity at surface (liquid or solid)3 - highConvective precipitation dominant.. Calibration by MW needed.TIR channel(s) in the 11 micrometers window. Frequent sampling (GEO) consistent with precipitation temporal variability
Sea surface temperature5 - marginalCloud sensitive.TIR window channel(s) around 11 micrometers .
Snow cover5 - marginalCloud sensitive.. Daylight only.VIS channel(s). Frequent sampling (GEO) improves probability of cloud-free views
Soil moisture at surface4 - fairCloud sensitive.. Index only.VIS and TIR window channels. Soil moisture inferred from thermal inertia, that is accurately measured by frequent sampling (GEO)
Integrated Water Vapour (IWV)4 - fairCloud sensitive.. Middle troposphere dominant.TIR channels in the water vapour band around 6.3 micrometers
Aerosol volcanic ash Total Column1 - primaryCloud sensitive.TIR channel(s). Frequent sampling (GEO) enables early detection of ash plumes
Wind (horizontal)3 - highCloud or water vapour tracers needed.VIS channel(s) and TIR channels around 6.3 and 11 micrometers. Frequent sampling (GEO) enables inference from cloud or water vapour pathces motion