Abstract
During the Spacelab 3 mission in May 1985, the ATMOS (Atmospheric Trace Molecule Spectroscopy) instrument recorded 19 sets of interferograms during solar occultations occurring in both the northern (∼30°N) and southern (∼47°S) hemispheres. The resulting high‐resolution (0.01 cm−1 unapodized) spectra, covering the 2.0‐ to 16‐μm region of the infrared, have provided concentration profiles for over 25 atmospheric species, with an average vertical resolution of ∼4.1 km. This paper reports on volume mixing ratio profiles for HCl and HF over the 15‐ to 60‐km altitude region, retrieved from the northern sunsets and the southern sunrises. While the southern profiles, because of a more limited data set, are accurate to ∼13% for HCl and ∼18% for HF, northern‐zonal distribution uncertainties are estimated to be ∼7% for HCl and ∼12% for HF; they agree well with recent balloon investigations at 30°N over the altitude range 15–40 km and show no tendency for a volume mixing ratio decrease at the level of the stratopause. The HF/HCl ratios deduced from the present measurements are also in good agreement with model predictions. Vertical profiles of ClONO2 and COF2, and upper limits for HOCl and ClO, obtained from ATMOS data by other investigators, are also summarized in order to evaluate the total chlorine budget in the stratosphere. This value approaches 2.6 parts per billion by volume, in good agreement with the total chlorine determined to be available from source species. The total atmospheric chlorine at 50 km is essentially all in the form of HCl.
Published Version
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