BackForwardInstrument:  SCR (Nimbus-5) 

Instrument details
Acronym SCR (Nimbus-5)
Full name Selective Chopper Radiometer
Purpose Atmospheric temperature profile
Short description 16-channel radiometer, with 4 channel implemented by a correlation spectrometer exploiting pressurised CO2 cells, the other 12 by a filter wedge spectrometer [see detailed characteristics below]
Background Follow-on of SCR and FWS flown on Nimbus-4
Scanning Technique Nadir only. IFOV of the 4 channels around 668.2 cm-1: 40 km; for all other 12 channels: 30 km
Resolution 30 km (40 km for pressure-modulated channels)
Coverage / Cycle Global in 10 days for cells of 100 km side
Mass 11.3 kg Power 15 W Data Rate

 

Providing Agency UKSA
Instrument Maturity
Utilization Period: 1973 to 1983-03-29
Last update: 2012-09-13
Detailed characteristics

Wavelength

Wave number

Bandwidth

NEΔT @ specified scene temperature

> 90.91 µm

 < 110 cm-1

-

0.6 K @ 250 K

49.50 µm

202 cm-1

18 cm-1

1.2 K @ 250 K

18.64 µm

536.4 cm-1

13.3 cm-1

0.1 K @ 250 K

14.97 µm

668.2 cm-1

3.4 cm-1

0.3 K @ 250 K

14.97 µm

668.2 cm-1

3.4 cm-1

0.2 K @ 250 K

14.97 µm

668.2 cm-1

3.4 cm-1

0.3 K @ 250 K

14.97 µm

668.2 cm-1

3.4 cm-1

0.4 K @ 250 K

14.96 µm

668.5 cm-1

9.0 cm-1

0.15 K @ 250 K

14.52 µm

688.5 cm-1

9.0 cm-1

0.11 K @ 250 K

14.14 µm

707.4 cm-1

9.3 cm-1

0.08 K @ 250 K

13.76 µm

726.5 cm-1

12.6 cm-1

0.2 K @ 250 K

11.64 µm

859 cm-1

89 cm-1

0.1 K @ 250 K

3.55 µm

2817 cm-1

50 cm-1

0.7 K @ 291 K

2.70 µm

3710 cm-1

72 cm-1

0.4 K @ 291 K

2.63 µm

3805 cm-1

100 cm-1

0.5 K @ 291 K

< 2.35 µm

> 4260 cm-1

-

1.5 K @ 291 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
  • 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.. Inaccurate in low troposphere.. Along-track only.Many TIR channels in the 15 micrometer band
Cloud cover4 - fairDiscontinuous coverage.. Along-track only.MWIR and TIR channels
Cloud top height3 - highDiscontinuous coverage.. Along-track only.TIR channels in window and in CO2 band for atmospheric column above cloud top
Cloud top temperature5 - marginalDiscontinuous coverage.. Along-track only.TIR window channel(s)
Cloud type4 - fairDiscontinuous coverage.. Along-track only.MWIR and TIR channels
Land surface temperature3 - highCloud sensitive.. Coarse spatial resolution.. Along-track only.MWIR and TIR window channels (high sensitivity to high temperature, cloud impact reduction, water vapour correction)
Sea surface temperature3 - highCloud sensitive.. Along-track only.MWIR and TIR window channels (cloud impact reduction, water vapour correction)
Specific humidity4 - fairCloud sensitive.. High troposphere only.. Along-track only.FIR channels in the water vapour rotational band around 18 micrometers
Integrated Water Vapour (IWV)3 - highCloud sensitive.. Along-track only.TIR and FIR channels from the 11 micrometers window into the 18 micrometers water vapour rotational band
Upward long-wave irradiance at TOA5 - marginalSpectral interpolation needed.. Along-track only.TIR and FIR channels in the 11 micrometers window, and in water vapour and CO2 bands around 6.3, 15 and 18 micrometers