BackForwardInstrument:  IMAGER (GOES 8-11) 

Instrument details
Acronym IMAGER (GOES 8-11)
Full name GOES Imager
Purpose Multi-purpose imagery and wind derivation by tracking clouds and water vapour features
Short description 5 channels covering VIS, MWIR and TIR [see detailed characteristics below]
Background Replacing VAS flown on GOES 4 to 7, separating the imagery from the sounding function.
Scanning Technique Mechanical, 3-axis stabilised satellite, E-W continuous, S-N stepping
Resolution 4.0 km for IR channels; 1.0 km for the VIS channel
Coverage / Cycle Full disk every 30 min.  Limited areas in correspondingly shorter time intervals
Mass 140 kg Power 130 W Data Rate 2.62 Mbps

 

Providing Agency NOAA
Instrument Maturity Flown on operational programme
Utilization Period: 1994-11-01 to 2011-12-05
Last update: 2016-10-16
Detailed characteristics
Central wavelength Spectral interval SNR or NEΔT @ specified input
0.65 µm 0.55 - 0.75 µm 250 @ 100 % albedo
3.90 µm 3.80 - 4.00 µm 0.11 K @ 300 K
6.75 µm 6.50 - 7.00 µm 0.14 K @ 300 K
10.70 µm 10.2 - 11.2 µm 0.09 K @ 300 K
11.95 µm 11.5 - 12.4 µm 0.70 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
Cloud cover3 - highNo specific limitation.VIS, MWIR and TIR channels
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
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
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
Aerosol volcanic ash (Total column)1 - primaryCloud sensitive.TIR channel(s). Frequent sampling (GEO) enables early detection of ash plumes
Integrated Water Vapour (IWV)2 - very highCloud sensitive.TIR channels around 6.3 micrometers and in the 11 micrometers split window
Sea surface temperature2 - very highCloud sensitive.MWIR and TIR window channels around 3.7 and 11 micrometers (cloud impact reduction, water vapour correction)
Cloud top temperature2 - very highNo specific limitation.TIR channels in window and water vapour band (for emissivity)
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 type3 - highNo specific limitation.VIS, MWIR and TIR channels
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
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
Downward long-wave irradiance at Earth surface4 - fairCloud sensitive.. Highly indirect.MWIR and TIR channels including the water vapour band
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
Soil moisture at surface4 - fairCloud sensitive.. Index only.VIS, MWIR and TIR channels. Soil moisture inferred from thermal inertia, that is accurately measured by frequent sampling (GEO)
Land surface temperature3 - highCloud sensitive.MWIR and TIR window channels (high sensitivity to high temperature, cloud impact reduction, water vapour correction)
Fire fractional cover4 - fairCloud sensitive.. Coarse spatial resolution.VIS, MWIR and TIR channels. Frequent sampling (GEO) enables early detection
Snow cover5 - marginalCloud sensitive.. Daylight only.VIS channel(s). Frequent sampling (GEO) improves probability of cloud-free views