BackForwardInstrument:  IMAGER (INSAT) 

Instrument details
Acronym IMAGER (INSAT)
Full name INSAT imager
Purpose Multi-purpose imagery and wind derivation by tracking clouds and water vapour features
Short description 6 VIS/IR channels [see detailed characteristics below, valid for INSAT-3D; in INSAT-3 DR and DS the MWIR channel is moved to 3.7-3.95 µm, and the 12 µm channel is stretched to 11.3-12.5 µm]
Background Replacing CCD and VHRR on INSAT-2D and INSAT-3A
Scanning Technique Mechanical, 3-axis stabilised satellite, E-W continuous, S-N stepping
Resolution 4.0 km for IR window channels; 1.0 km for VIS/SWIR channels; 8.0 km for water-vapour channel
Coverage / Cycle Full disk every 30 min.  Limited areas in correspondingly shorter time intervals
Mass 131 kg Power 85 W Data Rate 3.9 Mbps

 

Providing Agency ISRO
Instrument Maturity Flown on operational programme
Utilization Period: 2014-01-15 to ≥2028
Last update: 2018-06-10
Detailed characteristics
Central wavelength Spectral interval SNR or NEΔT @ specified input
0.65 µm 0.55 - 0.75 µm 900 @ 100 % albedo
1.625 µm 1.55 - 1.70 µm 220 @ 100 % albedo
3.82 µm 3.70 - 3.95 µm 0.5 K @ 300 K
6.8 µm 6.50 - 7.10 µm 0.25 K @ 300 K
10.8 µm 10.3 - 11.3 µm 0.26 K @ 300 K
12.0 µm 11.5 - 12.5 µm 0.28 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 - highCalibration by MW needed.. Convective precipitation dominant.TIR channels in the 11 micrometers window, and SWIR and the MWIR 3.7 window channel for cloud microphysics. Frequent sampling (GEO) is essential for accumulated precipitation
Cloud cover2 - 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 height3 - highNo specific limitation.TIR channels in window and water vapour band (for emissivity) to estimate cloud top height from its temperature
Cloud top temperature2 - very highNo specific limitation.TIR channels in window and water vapour band (for emissivity)
Cloud type2 - very highNo specific limitation.VIS, SWIR, MWIR and TIR channels
Downward long-wave irradiance at Earth surface4 - fairCloud sensitive.. Highly indirect.MWIR and TIR channels including the water vapour band
Fire fractional cover4 - fairCloud sensitive.. Coarse spatial resolution.VIS, MWIR and TIR channels. Frequent sampling (GEO) enables early detection
Fire radiative power2 - very highCloud sensitive.. Coarse spatial resolution.MWIR and TIR channels. Frequent sampling (GEO) enables early detection
Fire temperature2 - very highCloud sensitive.. Coarse spatial resolution.MWIR and TIR channels. Frequent sampling (GEO) enables early detection
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
Precipitation intensity at surface (liquid or solid)3 - highConvective precipitation dominant.. Calibration by MW needed.TIR channels in the 11 micrometers window, and SWIR and the MWIR 3.7 window channel for cloud microphysics. Frequent sampling (GEO) consistent with precipitation temporal variability
Sea surface temperature2 - 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. Frequent sampling (GEO) improves probability of cloud-free views
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)2 - very highCloud sensitive.TIR channels around 6.3 micrometers and in the 11 micrometers split window
Upward long-wave irradiance at TOA5 - marginalSpectral interpolation needed.MWIR and TIR channels in windows around 3.7 and 11 micrometers, and in the water vapour band around 6.3 micrometers
Upward long-wave irradiance at Earth surface4 - fairCloud sensitive.. Highly indirect.MWIR and TIR channels in windows around 3.7 and 11 micrometers, and in the water vapour band around 6.3 micrometers
Aerosol volcanic ash5 - marginalCloud sensitive.. Daylight only.VIS and SWIR channels
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