The total ozone abundance over Antarctica has decreased dramatically during the austral spring seasons of the past decade. Total ozone abundances observed in October, 1986 were only about half as large as those obtained in the late 1960's and early 1970's. Ozone plays an essential role in the Earth's ecology because of its absorption of ultraviolet radiation. A great deal of recent research has been directed towards understanding the cause of the change in the Antarctic ozone layer. Ground-based visible absorption spectroscopy will be used to measure the stratospheric column abundances of ozone, nitrogen dioxide (NO2) and clorine dioxide (OClO). This will provide a means of simultaneously measuring the ozone change and the abundances of both reactive nitrogen and reactive chlorine species. Possible correlations between simultaneous measurements of the three constituents are of particular value in distinguishing between proposed mechanisms of the ozone depletion. Such measurements can be carried out by using the direct light from the sun or moon (thus providing information on the diurnal variations of these species) or by measuring the scattered light from the zenith sky. The planned research consists of an extended series of visible absorption measurements at McMurdo Station during August, September, and October, 1987.
