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Solar Backscatter Ultraviolet/Total Ozone Mapping Spectrometer (SBUV/TOMS)

NSSDCA ID: 1978-098A-09

Mission Name: Nimbus 7
Principal Investigator:Dr. Donald F. Heath


The objectives of the Solar Backscatter Ultraviolet and Total Ozone Mapping Spectrometer (SBUV/TOMS) were to determine the vertical distribution of ozone, map the total ozone content, and monitor the incident solar ultraviolet (UV) irradiance and ultraviolet radiation backscattered from the earth. The SBUV consisted of a double Ebert-Fastie spectrometer and a filter photometer similar to the BUV on Nimbus 4. The SBUV spectrometer measured solar UV backscattered by the earth's atmosphere at 12 wavelengths between 0.25 and 0.34 micrometer, with a spectral bandpass of 0.001 micrometer. The SBUV used three detectors: a photomultiplier tube (PMT) and a photodiode for the monochromator, and one photodiode for the photometer. Both the monochromator and the photometer have chopper wheels operating at 25 Hz. The SBUV used a depolarizer to eliminate the sensitivity of the grating monochromator to polarization of the backscattered radiation. The instrument's field of view (FOV) at nadir was 0.20 rad. A roughened aluminum diffuser plate viewed the sun for solar-spectral irradiance measurements and for calibration by viewing a mercury-argon lamp. The diffuser plate was driven by a stepper motor to three postions on command: SBUV, TOMS, and STOW. The contribution functions for the eight shortest wavelengths were centered at levels ranging from 55 to 28 km and were used to infer the vertical ozone profile. The four longest wavelengths had contribution functions in the troposphere which were used to compute the total ozone amount. The SBUV spectrometer had a second mode of operation that allowed a continuous solar-spectral scan from 0.16 to 0.4 micrometer for detailed examination of the extraterrestrial solar spectrum and its temporal variations. A parallel photometer channel at 0.343 micrometer measured the reflectivity of the atmosphere's lower boundary in the same 0.21-rad FOV. The TOMS was a single Ebert-Fastie spectrometer with a fixed grating and an array of exit slits. The TOMS step-scanned across the orbital track 51 deg from the nadir in 3-deg steps with an FOV of approximately 0.052 rad. At each scan position, the earth radiance was monitored at six wavelengths between 0.31 and 0.38 micrometer to infer the total ozone amount. The TOMS completed a cross scan in eight seconds, with one second for retrace, to record 35 scenes per scan. At each scene, a chopper sequentially sampled all six wavelengths four times. The TOMS used the same type of PMT as SBUV, and had a separate mercury-argon lamp for wavelength calibration and a separate depolarizer. The TOMS shared the diffuser plate with SBUV. Both SBUV and TOMS had five scanner modes and a shared electronics module. For a more detailed description, see Section 7 in "The Nimbus 7 Users' Guide" (TRF B30045), available from NSSDC.

Alternate Names

  • Nimbus7/TOMS
  • SBUV
  • TOMS

Facts in Brief

Mass: 20 kg
Power (avg): 20 W
Bit rate (avg): 4 kbps

Funding Agency

  • NASA-Office of Space Science (United States)


  • Earth Science: Atmospheric Chemistry
  • Solar Physics: Ultraviolet

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Donald F. HeathTeam LeaderNASA Goddard Space Flight Center
Dr. William L. ImhofTeam MemberLockheed Palo Alto
Dr. Alex E. S. GreenTeam MemberUniversity of
Dr. Arlin J. KruegerTeam MemberNASA Goddard Space Flight
Dr. Arthur D. BelmontTeam MemberControl Data Corporation
Dr. Carlton L. MateerTeam MemberEnvironment Canada
Dr. Derek M. CunnoldTeam MemberGeorgia Institute of
Mr. Alvin J. MillerTeam MemberNOAA National Meterological Center
Dr. Richard D. McPetersTeam MemberNASA Goddard Space Flight
Dr. Ashok G. KaveeshwarTeam MemberSystems and Applied Sciences
Dr. Albert J. Fleig, Jr.Team MemberNASA Goddard Space Flight
Dr. Hong Woo ParkTeam MemberSystems and Applied Sciences Corp
Dr. Kenneth F. KlenkTeam MemberSystems and Applied Sciences
Dr. P. K. BhartiaTeam MemberSystems and Applied Sciences

Selected References

  • Markert, T. H., et al., Solar backscatter ultraviolet and total ozone mapping spectrometer (SBUV/TOMS) for Nimbus G, Opt. Engin., 14, No. 4, 323-331, doi:10.1117/12.7971839, July-Aug. 1975.
  • Fleig, A. J., et al., User's guide for SBUV/TOMS ozone derivative products, NASA, RP-1116, Wash., DC, Jan. 1984.
  • Krueger, A., ed., Scientific and operational requirements for TOMS data, NASA-GSFC, CP-2497, Greenbelt, Md, Sept. 1987.
  • Cebula, R. P., et al., Characterization of the Nimbus-7 SBUV radiometer for the long-term monitoring of stratospheric ozone, J. Atmos. Oceanic Technol., 5, 215-227, doi:10.1175/1520-0426(1988)005<0215:COTNSR>2.0.CO;2, Apr. 1988.
  • Heath, D., et al., The solar backscatter ultraviolet (SBUV) and total ozone mapping spectrometer (TOMS) 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. 175, Aug. 1978.
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