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Infrared spectroscopic detection of sulfur hexafluoride (SF sub 6 ) in the lower stratosphere and upper troposphere

Journal Article · · Journal of Geophysical Research; (United States)
 [1]; ;  [2]
  1. NASA Langley Research Center, Hampton, VA (United States)
  2. California Inst. of Tech., Pasadena (United States)
Absorption by sulfur hexafluoride (SF{sub 6}) has been detected in high-resolution infrared solar spectra of the lower stratosphere and upper troposphere. The identification is based on measurements of the intense, unresolved {nu}{sub 3} band Q branch at 947.9 cm{sup {minus}1} in solar occultation spectra recorded near 31{degree}N and 47{degree}S latitude by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer on April 30 to May 1, 1985, during the Spacelab 3 shuttle mission. Vertical SF{sub 6} volume mixing ratio profiles have been retrieved using an onion-peeling nonlinear least squares spectral fitting procedure with SF{sub 6} line-by-line spectroscopic parameters generated recently by Bobin and coworkers from their analysis of the SF{sub 6} {nu}{sub 3} band. Between 12 and 18 km altitude, the region over which the retrievals are most accurate (about {plus minus} 26% one sigma), the SF{sub 6} volume mixing ratio is independent of altitude with an average measured value of 1.42 parts per trillion by volume (pptv) at 31{degree}N latitude. There is evidence for a decline in the SF{sub 6} volume mixing ratio with increasing altitude between 18 and 22 km, but the results are not conclusive because of the weakness of the absorption. Absorption by the SF{sub 6} Q branch is below the noise level of the spectra at tangent heights above {approximately} 22 km. The measurements are compared with previously reported values and discussed in terms of the atmospheric lifetime of SF{sub 6}, the long-term trend of atmospheric SF{sub 6}, and the possible role of SF{sub 6} as an atmospheric greenhouse gas.
OSTI ID:
5088095
Journal Information:
Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:D5; ISSN 0148-0227; ISSN JGREA
Country of Publication:
United States
Language:
English