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TIROS Operational Vertical Sounder

NSSDCA ID: 1978-096A-02

Mission Name: TIROS-N
Principal Investigator:


The TIROS Operational Vertical Sounder (TOVS) consisted of three instruments designed to determine radiances needed to calculate temperature and humidity profiles of the atmosphere from the surface to the stratosphere (approximately 1 mb). The first instrument was the second version of the high-resolution infrared spectrometer (HIRS/2). The HIRS was tested on the Nimbus 6. The HIRS/2 had 20 channels in the following spectral intervals: channels 1 through 5 , the 15-micrometer CO2 bands (15.0, 14.7, 14.5, 14.2, and 14.0); channels 6 and 7, the 13.7 and 13.4-micrometer CO2/H2O bands; channel 8, the 11.1-micrometer window region; channel 9, the 9.7-micrometer ozone band; channels 10 through 12, the 6-micrometer water vapor bands (8.3, 7.3, and 6.7); channels 13 and 14, the 4.57 and 4.52-micrometer N2O bands; channels 15 and 16, the 4.46 and 4.40-micrometer CO2/N2O bands; channel 17, the 4.24-micrometer CO2 band; channels 18 and 19, the 4.0 and 3.7-micrometer window bands; and channel 20, the 0.70-micrometer window region. The second instrument, the stratospheric sounding unit (SSU), was provided by the British Meteorological Office. It was similar to the pressure-modulated radiometer (PMR) flown on Nimbus 6. The SSU operated at three 15.0-micrometer channels using selective absorption, passing the incoming radiation through three pressure-modulated cells containing CO2. The third instrument, the microwave sounding unit (MSU), was similar to the scanning microwave spectrometer (SCAMS) flown on Nimbus 6. The MSU had one channel in the 50.31-GHz window region and three channels in the 55-GHz oxygen band (53.73, 54.96, 57.95) to obtain temperature profiles which were free of cloud interference. The instruments were cross-course scanning devices utilizing a step scan to provide a transverse scan, while the orbital motion of the satellite provided scanning in the orthogonal direction. The HIRS/2 had a field of view (FOV) 30 km in diameter at nadir, whereas the MSU had a FOV of 110 km in diameter. The HIRS/2 sampled 56 FOVs in each scan line about 2250 km wide, and the MSU sampled 11 FOVs along the swath with the same width. Each SSU scan line had 8 FOVs with a width of 1500 km. This experiment was also flown on other TIROS-N/NOAA series spacecraft. For a more detailed description, see W. L. Smith, "The TIROS-N operational vertical sounder," Bull. Am. Meteorol. Soc., v. 60, pp. 1177-1187, 1979. Archival data are available from the Satellite Data Services Division, National Climatic Center, NOAA, Washington, D.C.

Alternate Names

  • TOVS

Funding Agency

  • NOAA National Environmental Satellite Service (United States)


    Additional Information

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



    NameRoleOriginal AffiliationE-mail
    Principal InvestigatorNOAA National Environmental Satellite, Data and Information Service
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