Simultaneous spectroscopic measurements of stratospheric species: O3, CH4, CO, CO2, N2O, H2O, HCl, and HF at northern and southern mid‐latitudes

Abstract

Near‐infrared solar absorption spectra have been recorded in the course of balloon flights from Palestine, Texas, (32°N latitude) in May 1976, and Broken Hill, Australia, (30°S latitude) in March 1977. The northern flight was made at a float altitude of 37 km and covered the spectral region from 1800 cm−l to 3600 cm−1, which encompasses infrared transitions of O3, CH4, CO, CO2, N2O, H2O, and HCl. The flight in the southern hemisphere, from a float altitude of 39 km, covered the spectral region from 2800 cm−l to 4500 cm−1, which includes useful transitions for all of the above gases (with the exception of CO) and encompasses as well the 1‐0 fundamental band for HF. Both sets of spectra were acquired at sunset by using a high‐resolution (0.13 cm−1) Michelson interferometer. The simultaneous profiles of concentration derived from the spectra for the individual gases covered in each flight are presented and discussed. While the results show few differences between the profiles at the northern and southern latitudes, there are several aspects of general importance; these include lower values for stratospheric CO than had previously been reported (i.e., ∼10 ppbv), and water vapor profiles in both hemispheres showing an increase with altitude considerably in excess of that to be expected from CH4 oxidation alone. The shape of the profile for HF was found to be consistent with model predictions, but the HF concentrations were lower by a factor of 3 or 4 than those predicted.