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Stratospheric observations of CH 3 D and HDO from ATMOS infrared solar spectra: Enrichments of deuterium in methane and implications for HD
Author(s) -
Irion F. W.,
Moyer E. J.,
Gunson M. R.,
Rinsland C. P.,
Yung Y. L.,
Michelsen H. A.,
Salawitch R. J.,
Chang A. Y.,
Newchurch M. J.,
Abbas M. M.,
Abrams M. C.,
Zander R.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl01402
Subject(s) - mixing ratio , stratosphere , methane , isotopologue , deuterium , spectral line , analytical chemistry (journal) , atmospheric methane , infrared spectroscopy , chemistry , atmospheric sciences , physics , atomic physics , astronomy , environmental chemistry , organic chemistry
Stratospheric mixing ratios of CF 3 D from 100 mb to 17 mb (≈ 15 to 28 km) and HDO from 100 mb to 10 mb (≈ 15 to 32 km) have been inferred from high resolution solar occultation infrared spectra from the Atmospheric Trace MOlecule Spectroscopy (ATMOS) Fourier‐transform interferometer. The spectra, taken on board the Space Shuttle during the Spacelab 3 and ATLAS‐1, ‐2, and ‐3 missions, extend in latitude from 70°S to 65°N. We find CH 3 D entering the stratosphere at an average mixing ratio of (9.9±0.8) × 10 −10 with a D/H ratio in methane (7.1±7.4)% less than that in Standard Mean Ocean Water (SMOW) (1σ combined precision and systematic error). In the mid to lower stratosphere, the average lifetime of CH 3 D is found to be (1.19±0.02) times that of CH 4 , resulting in an increasing D/H ratio in methane as air “ages” and the methane mixing ratio decreases. We find an average of (1.0±0.1) molecules of stratospheric HDO are produced for each CH 3 D destroyed (1σ combined precision and systematic error), indicating that the rate of HDO production is approximately equal to the rate of CH 3 D destruction. Assuming negligible amounts of deuterium in species other than HDO, CH 3 D and HD, this limits the possible change in the stratospheric HD mixing ratio below about 10 mb to be ±0.1 molecules HD created per molecule CH 3 D destroyed.