BackForwardInstrument:  IRS 

Instrument details
Acronym IRS
Full name Infra Red Sounder
Purpose Temperature/humidity sounding and wind profile derivation by tracking water vapour features
Short description Interferometer with large detector arrays for simultaneous sounding of more pixels [see detailed characteristics below]
Background New development
Scanning Technique The disk is split in 4 latitude belts, and is covered at 6-hour intervals; but not all at the same time. The northermost belt, that includes Europe, is imaged at 30-min intervals for the whole 6-hour period (12 images). The following belt is covered simultaneously with the first one, but the 30-min sequence is limited to 5 images. The third belt is covered after the second, by a sequence of 4 images. The southernmost belt is covered after the third, by only 3 images (the minimum to track a water-vapour patch)
Resolution 4.0 km at s.s.p.
Coverage / Cycle 30 min for the northermost 1/4 of the disk (that includes the European area). 6 hours for the whole disk
Mass 400 kg Power 750 W Data Rate

 

Providing Agency ESA
Instrument Maturity Demonstrated by simulations
Utilization Period: ≥2023 to ≥2039
Last update: 2020-02-18
Detailed characteristics

Wavelength

Wave number

Spectral resolution (unapodised)

NE∆T @ specified scene temperature

14.29 μm

700 cm-1

0.625 cm-1

14.00 μm

714 cm-1

0.625 cm-1

13.99 μm

715 cm-1

0.625 cm-1

13.72 μm

729 cm-1

0.625 cm-1

13.70 μm

730 cm-1

0.625 cm-1

13.00 μm

769 cm-1

0.625 cm-1

12.99 μm

770 cm-1

0.625 cm-1

9.62 μm

1040 cm-1

0.625 cm-1

8.94 μm

1118 cm-1

0.625 cm-1

8.26 μm

1210 cm-1

0.625 cm-1

6.25 μm

1600 cm-1

0.625 cm-1

6.13 μm

1630 cm-1

0.625 cm-1

5.71 μm

1750 cm-1

0.625 cm-1

5.34 μm

1871 cm-1

0.625 cm-1

5.05 μm

1980 cm-1

0.625 cm-1

4.69 μm

2134 cm-1

0.625 cm-1

4.60 μm

2175 cm-1

0.625 cm-1

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
  • Height of the top of PBL
  • Height of the tropopause
  • Integrated Water Vapour (IWV)
  • Specific humidity
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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 temperature1 - primaryCloud sensitive.MWIR and TIR spectrometry in the CO2 4.3 and 15 micrometer bands. Frequent sampling (GEO) enables monitoring instability onset
C2H2 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. C2H2 lines around 7.5 and 13.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
C2H6 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. C2H6 lines around 12 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
CFC-11 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. CFC-11 lines around 9.2 and 11.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
CFC-12 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. CFC-12 lines around 8.8 and 10.8 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
CH4 Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.MWIR and TIR spectrometry. CH4 lines around 4.3 and 7.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
ClONO2 Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.MWIR and TIR spectrometry. ClONO2 lines around 5.7, 7.7 and 12.5 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
Cloud cover3 - highDiscontinuous coverage.MWIR and TIR spectrometry
Cloud top height2 - very highDiscontinuous coverage.MWIR and TIR spectrometry in window and water vapour band (for emissivity) to estimate cloud top height from its temperature
Cloud top temperature1 - primaryDiscontinuous coverage.TIR spectrometry in window and water vapour band (for emissivity)
Cloud type4 - fairDiscontinuous coverage.MWIR and TIR spectrometry
CO Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.MWIR spectrometry. CO lines around 4.6. Frequent sampling (GEO) enables monitoring diurnal variations
CO2 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. CO2 lines around 15 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
COS Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. COS lines around 11.6 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
Downward long-wave irradiance at Earth surface1 - primaryCloud sensitive.. Highly indirect.MWIR and TIR spectrometry including water vapour and CO2 bands
H2O Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.MWIR/TIR spectrometry in a range centred on 6.3 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
Height of the top of PBL4 - fairCloud sensitive.MWIR and TIR spectrometry. Height of PBL top from temperature profile. Frequent sampling (GEO) enables monitoring the PBL evolution
Height of the tropopause4 - fairCloud sensitive.TIR spectrometry. Height of tropopause from temperature profile. Frequent sampling (GEO) enables monitoring the tropopause evolution
HNO3 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.MWIR and TIR spectrometry. HNO3 lines around 5.9, 7.6 and 11.3 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
Land surface temperature2 - very highCloud sensitive.. Coarse spatial resolution.MWIR and TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections)
Long-wave Earth surface emissivity1 - primaryCloud sensitive.. Long time series needed.MWIR and TIR spectrometry measuring land temperature in many windows. Emissivity inferred by statistical analysis
N2O Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.MWIR and TIR spectrometry. N2O lines around 4.5 and 7.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
3 - highCloud sensitive.. Coarse vertical resolution.MWIR and TIR spectrometry. N2O5 lines around 5.8 and 8 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
NO Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.MWIR spectrometry. NO lines around 5.3 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
NO2 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. NO2 lines around 6.1 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
NO2 Total Column4 - fairCloud sensitive.TIR spectrometry. NO2 lines around 6.1 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
O3 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. Ozone band around 9.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
O3 Total Column3 - highCloud sensitive.TIR channel(s). Ozone lines in band around 9.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
PAN Mole Fraction3 - highCloud sensitive.. Coarse spatial resolution.MWIR and TIR spectrometry. PAN lines around 5.7, 8.6 and 12.5 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations
PSC occurrence2 - very highMarginal view from GEO.. Coarse vertical resolution.MWIR and TIR spectroscopy
Sea surface temperature1 - primaryCloud sensitive.MWIR and TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections)
SF6 Mole Fraction3 - highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. SF6 lines around 10.5 micrometers. Frequent sampling (GEO) for diurnal variations
SO2 Mole Fraction2 - very highCloud sensitive.. Coarse vertical resolution.TIR spectrometry. SO2 lines around 7.3 and 8.6 micrometers. Frequent sampling (GEO) for sources monitoring
SO2 Total Column2 - very highCloud sensitive.TIR spectrometry. SO2 lines around 7.3 and 8.6 micrometers. Frequent sampling (GEO) for sources monitoring
Specific humidity1 - primaryCloud sensitive.TIR spectrometry in the water vapour band around 6.3 micrometers. Frequent sampling (GEO) enables monitoring instability onset
Integrated Water Vapour (IWV)2 - very highCloud sensitive.TIR spectrometry in the bands around 6.3 and above 11 micrometers. Frequent sampling (GEO) enables monitoring instability onset
Temperature of the tropopause3 - highCloud sensitive.TIR spectrometry. Tropopause temperature from temperature profile. Frequent sampling (GEO) enables monitoring the tropopause evolution
Upward spectral radiance at TOA2 - very highMissing all Short-waves.MWIR and TIR spectrometry resolving water vapour lines in the bands around 6.3 micrometers and 11 to 15 micrometers; and other greenhouse gases
Upward long-wave irradiance at TOA3 - highSpectral interpolation needed.MWIR and TIR spectrometry in the windows regions around 3.7 and 11 micrometers, and in water vapour and CO2 bands around 4,3, 6.3 and 15 micrometers
Upward long-wave irradiance at Earth surface1 - primaryCloud 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
Wind (horizontal)2 - very highCloud sensitive.. Water vapour tracers needed.TIR spectrometry in the 6.3 micrometers band. Wind profile in clear air by tracking water vapour patches in the humidity profile