BackForwardInstrument:  HIRS 

Instrument details
Acronym HIRS
Full name High-resolution Infra-Red Sounder
Purpose Temperature/humidity sounding
Short description Filter radiometer, 17 channels (including one VIS) [see detailed characteristics below]
Background Evolution of the 7-channel ITPR flown on Nimbus-5
Scanning Technique Cross-track: 42 fields of view, step-and-dwell, 1820 km swath. Along-track: one 32-km line each 5.2 s
Resolution 25 km at s.s.p.
Coverage / Cycle Near-global coverage twice/day
Mass 13.5 kg Power 10 W Data Rate 10.8 kbps

 

Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 1975 to 1983-03-29
Last update: 2012-09-05
Detailed characteristics

Wavelength

Wave number

Bandwidth

SNR @ specified input

15.0 µm

668 cm-1

2.8 cm-1

…. @ ….. mW m-2 sr-1 μm-1

14.7 µm

679 cm-1

13.7 cm-1

…. @ ….. mW m-2 sr-1 μm-1

14.4 µm

690 cm-1

12.6 cm-1

…. @ ….. mW m-2 sr-1 μm-1

14.2 µm

702 cm-1

15.9 cm-1

…. @ ….. mW m-2 sr-1 μm-1

14.0 µm

716 cm-1

17.5 cm-1

…. @ ….. mW m-2 sr-1 μm-1

13.6 µm

733 cm-1

17.6 cm-1

…. @ ….. mW m-2 sr-1 μm-1

13.4 µm

749 cm-1

18.4 cm-1

…. @ ….. mW m-2 sr-1 μm-1

11.0 µm

900 cm-1

34.6 cm-1

…. @ ….. mW m-2 sr-1 μm-1

8.20 µm

1224 cm-1

63.4 cm-1

…. @ ….. mW m-2 sr-1 μm-1

6.70 µm

1496 cm-1

87.6 cm-1

…. @ ….. mW m-2 sr-1 μm-1

4.57 µm

2190 cm-1

20.6 cm-1

…. @ ….. mW m-2 sr-1 μm-1

4.52 µm

2212 cm-1

22.5 cm-1

…. @ ….. mW m-2 sr-1 μm-1

4.46 µm

2242 cm-1

21.6 cm-1

…. @ ….. mW m-2 sr-1 μm-1

4.40 µm

2275 cm-1

35.2 cm-1

…. @ ….. mW m-2 sr-1 μm-1

4.24 µm

2357 cm-1

23.0 cm-1

…. @ ….. mW m-2 sr-1 μm-1

3.71 µm

2692 cm-1

297 cm-1

…. @ ….. mW m-2 sr-1 μm-1

0.69 µm

14,443 cm-1

892 cm-1

…. @ …. % albedo

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)
  • Specific humidity
Secondary mission objectives
  • Sea surface temperature
Opportunity objectives
  • Cloud cover
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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
Atmospheric temperature3 - highCloud sensitive.. Coarse vertical resolution.Many MWIR and TIR channels in the 4.3 and 15 micrometer bands
Integrated Water Vapour (IWV)3 - highCloud sensitive.. Inaccurate in high troposphere.TIR channels around 6.3 micrometers and in the 11 micrometers split window
Specific humidity3 - highCloud sensitive.. Very coarse vertical resolution.. Middle troposphere only.TIR channels in the water vapour band around 6.3 micrometers
Sea surface temperature3 - highCloud sensitive.MWIR and TIR window channels (cloud impact reduction, water vapour correction)
Cloud cover4 - fairDiscontinuous coverage.MWIR and TIR channels
Cloud top temperature3 - highDiscontinuous coverage.TIR channels in window and water vapour band (for emissivity)
Cloud top height2 - very highDiscontinuous coverage.TIR channels in window and water vapour band (for emissivity) for temperature; and in CO2 band for atmospheric column above cloud top
Cloud type4 - fairDiscontinuous coverage.MWIR and TIR channels
Upward long-wave irradiance at TOA4 - fairSpectral interpolation needed.MWIR and TIR channels in windows around 3.7 and 11 micrometers, and in water vapour and CO2 bands around 4,3, 6.3 and 15 micrometers
Downward long-wave irradiance at Earth surface3 - highCloud sensitive.. Highly indirect.MWIR and TIR channels including water vapour and CO2 bands
Upward long-wave irradiance at Earth surface3 - highCloud sensitive.. Highly indirect.MWIR and TIR channels in windows around 3.7 and 11 micrometers, and in water vapour and CO2 bands around 4,3, 6.3 and 15 micrometers
Land surface temperature3 - highCloud sensitive.. Coarse spatial resolution.MWIR and TIR window channels (high sensitivity to high temperature, cloud impact reduction, water vapour correction)