Infrared aircraft measurements of stratospheric composition over Antarctica during September 1987

The Jet Propulsion Laboratory Mark IV interferometer recorded high‐resolution, infrared solar spectra from the NASA DC‐8 aircraft during flights over Antarctica in September 1987. The atmospheric absorption features in these spectra have been analyzed to determine the burdens of O 3 , NO, NO 2 , HNO 3 , ClNO 3 , HCl, HF, CO 2 , CH 4 , N 2 O, HCN, CO, H 2 O, CFCl 3 , and CF 2 Cl 2 . The results show a “collar” of high HNO 3 and ClNO 3 surrounding a “core” in which the burdens of these and of HCl and NO 2 are very low. Clear increases in the burdens of HF and HNO 3 were observed during the course of September in the vortex core. HCl and NO 2 exhibited smaller, less significant increases. The burdens of the tropospheric source gases, N 2 O, CH 4 , HCN, CFCl 3 , CF 2 Cl 2 , CO, and H 2 O, were observed to be much smaller over Antarctica than at mid‐latitudes. This, together with the fact that HF over Antarctica was more than double its mid‐latitude value, suggests that downwelling had occurred.