Abstract 9615198 Deshler The annual stratospheric ozone hole above Antarctica is driven by chlorine compounds which interact on the surfaces of the polar stratospheric clouds which form during the polar winter. It is for this reason that the hole appears in the austral spring and that ozone depletion is much more severe in polar regions than elsewhere. This investigation provides detailed information on the actual cloud particles and the distribution of the clouds and the ozone by using balloon borne instruments. The measurements will provide vertical profiles of both the PSCs and ozone, size distributions of the PSC particles and some information on their composition and physical state (liquid or solid). The project is enhanced by cooperation with an Italian investigator who operates a lidar system in McMurdo. The project contributes to the WMO/UNEP Network for the Detection of Stratospheric Change and the Global Change Initiative. ***