In Aug 1986, four scientific experiments were flown to
McMurdo Station, Antarctica, to try to understand the recently-discovered Antarctic Ozone Hole phenomenon.
1) MkIV Interferometer (JPL)
2) NOAA Visible grating spectrometer (NOAA)
3) Microwave radiometer (SUNY)
4) Ozone sondes (U Wyoming)
At that time there were three main theories:
1) Chemical loss due to Cl and Br
2) Chemical loss due to NOx transported down from the mesosphere
3) Lofting ozone-poor tropospheric air into the lower stratosphere.
The low amounts of NO2 observed by JPL and NOAA argued against (2). The large amounts of HNO3 and HF and the low amounts of N2O measured by JPL argued against (3). The very low HCl measured by JPL in early September, 1986, together with the large amounts of ClO measured by SUNY pointed toward (1) as the main cause of the ozone loss. This was confirmed by the 1987 Antarctic Airborne Ozone Experiment (AAOE) in which in-situ experiments directly measured spatial anti-correlations of O3 and ClO.
Miscellaneous photographs below