BackForwardInstrument:  IRIS-D 

Instrument details
Acronym IRIS-D
Full name Infra-Red Interferometer Spectrometer - D
Purpose Exploration of the IR spectrum
Short description Interferometer for the spectral range 5.0-25 µm (400-2000 cm-1), spectral resolution 1.4 cm-1 (unapodised)
Background Follow-on of IRIS-B flown on Nimbus-3. Actually stopped on 25 January 1972 because of problems with the platform power
Scanning Technique Non-scanning, along-track sampling at 100 km intervals
Resolution 94 km
Coverage / Cycle Global in 10 days for cells of 100 km side
Mass 22 kg Power 28 W Data Rate 3.75 kbps

 

Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 1970 to 1980-09-30
Last update: 2012-09-05
Detailed characteristics
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
  • Cross-nadir infrared sounder, possibly including VIS channels
Mission objectives
Primary mission objectives
  • Atmospheric temperature
  • Integrated Water Vapour (IWV)
  • Sea surface temperature
  • Specific humidity
  • Upward long-wave irradiance at TOA
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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 top height2 - very highDiscontinuous coverage.. Along-track only.MWIR and TIR spectrometry in window and water vapour band (for emissivity) to estimate cloud top height from its temperature
Atmospheric temperature2 - very highCloud sensitive.. Inaccurate in low troposphere.. Along-track only.TIR spectrometry in the 15 micrometer band
Integrated Water Vapour (IWV)1 - primaryCloud sensitive.. Along-track only.TIR and FIR spectrometry in bands around 6.3 and 18 micrometers
Specific humidity2 - very highCloud sensitive.. Along-track only.TIR and FIR spectrometry in bands around 6.3 and 18 micrometers
Sea surface temperature3 - highCloud sensitive.. Along-track only.TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections)
Cloud cover5 - marginalDiscontinuous coverage.. Along-track only.TIR channel(s)
Cloud top temperature1 - primaryDiscontinuous coverage.. Along-track only.TIR spectrometry in window and water vapour band (for emissivity)
Upward long-wave irradiance at TOA3 - highSpectral interpolation needed.. Along-track only.TIR and FIR spectrometry in the 11 micrometers window region, and in water vapour and CO2 bands around 6.3, 15 and 18 micrometers
Downward long-wave irradiance at Earth surface2 - very highCloud sensitive.. Highly indirect.. Along-track only.MWIR and TIR spectrometry including water vapour and CO2 bands
Upward long-wave irradiance at Earth surface2 - very highCloud sensitive.. Highly indirect.. Along-track only.TIR spectrometry covering the 11 micrometers window region and the water vapour and CO2 bands around 6.3 and 15 micrometers
Long-wave Earth surface emissivity2 - very highCloud sensitive.. Long time series needed.. Along-track only.MWIR and TIR spectrometry measuring land temperature in many windows. Emissivity inferred by statistical analysis
Land surface temperature4 - fairCloud sensitive.. Coarse spatial resolution.. Along-track only.TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections)