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Stratospheric and Mesospheric Sounder (SAMS)

NSSDCA ID: 1978-098A-02

Mission Name: Nimbus 7
Principal Investigators:Prof. John T. Houghton
Principal Investigators:Dr. Fredric W. Taylor


The objective of the Stratospheric and Mesospheric Sounder (SAMS), a pressure broadening spectral radiometer, was to observe emission from the limb of the atmosphere through seven pressure-modulated cells and six detectors in order to determine temperature and vertical concentrations of H2O, N2O, CH4, CO, and NO in the stratosphere and mesosphere. Measurements of zonal wind in this region were attempted by observing the Doppler shift of atmospheric emission lines. Radiation from the limb of the atmosphere was incident on a scan mirror in front of a 15-cm aperture telescope. The scan mirror scanned the limb, viewed space for calibration, and viewed the atmosphere obliquely to obtain vertical profiles. There were three adjacent fields of view, each 28 by 2.8 mrad (corresponding to 100 km by 10 km at the limb). The FOVs were focused onto a field-splitting mirror by the telescope which directed radiation to six detectors. Seperation into channels was accomplished through dichroic beam splitters. There were seven pressure modulator cells (PMC), two containing CO2, the remainder N2O, NO, CH4, CO, H2O. Pressure in the cells could be varied on command by changing the temperature of a small container of molecular sieve material attached to each PMC. The spectral parameters for the H2O channel were 2.7 micrometers and 25 to 100 micrometers. All other channels lay within the range 4.1 to 15 micrometers. A chopper operating at 250 Hz within the telescope, allowed the measurement of two separate signals from all detectors, one at 250 Hz and one at the PMC frequency. Comparison of these signals permitted the elimination of emission from interfering gases within a particular spectral interval. In front of the chopper, a small black body at known temperature was introduced for calibration. Accurate measurement of the atmospheric pressure at the level being viewed was obtained from the two signals from one CO2 channel. For a more detailed description, see Section 6 in "The Nimbus 7 Users' Guide" (TRF B30045), available from NSSDC.

Alternate Names

  • Nimbus7/SAMS
  • SAMS

Facts in Brief

Mass: 23.6 kg
Power (avg): 20 W
Bit rate (avg): 25 kbps

Funding Agency

  • NASA-Office of Space Science (United States)


  • Earth Science: Atmospheric Chemistry
  • Earth Science: Atmospheric Dynamics

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Mr. John W. Lovelace, Jr.General ContactNASA Goddard Space Flight Center
Dr. Guy D. PeskettOther InvestigatorOxford
Dr. Clive D. RodgersOther InvestigatorOxford
Dr. E. Jim. WilliamsonOther InvestigatorOxford
Dr. John J. BarnettOther InvestigatorOxford
Mr. John G. WhitneyOther InvestigatorOxford
Dr. Roderic L. JonesOther InvestigatorOxford University
Dr. Marie CorneyOther InvestigatorOxford
Dr. Robert A. BrownOther InvestigatorUniversity of
Prof. John T. HoughtonPrincipal InvestigatorOxford
Dr. Fredric W. TaylorPrincipal InvestigatorOxford

Selected References

  • Rodgers, C. D., et al., Retrieval of temperature and composition from Nimbus 7 SAMS measurements, J. Geophys. Res., 89, No. D4, 5280-5286, doi:10.1029/JD089iD04p05280, June 1984.
  • Wale, M. J., and G. D. Peskett, Some aspects of the design and behavior of the stratospheric and mesospheric sounder, J. Geophys. Res., 89, No. D4, 5287-5293, doi:10.1029/JD089iD04p05287, June 1984.
  • Taylor, F. W., et al., Nimbus-7 stratospheric and mesospheric sounder (SAMS) experiment data user's guide, NASA, RP-1221, Washington, DC, May 1989.
  • Drummond, J. R., et al., The stratospheric and mesospheric sounder (SAMS) experiment, in The Nimbus 7 Users' Guide, edited by C.R. Madrid, Management and Technical Services Company, Beltsville, MD, The Landsat/Nimbus Project, NASA/GSFC, p. 139, Aug. 1978.
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