| Summary: | The factors that contributed to the enhanced ozone depletion during the 1995-96 Arctic winter are presented. Temperature, CIO, 03, and aerosol extinction from the Upper Atmosphere Research Satellite (UARS), Stratospheric Aerosol Measurement IT (SAM IT), and Polar Ozone and Aerosol Measurement IT (POAM IT) experiments at latitudes near 20 km are interrelated. The conditions of the stratosphere within the polar vortex are analyzed for both 1991-92 and 1995-96. Both low temperatures and enhanced extinction values extended much later in the 1996 winter than in 1989 or 1992. The enhanced extinction suggests that PSCs continued to form throughout the 1995-96 winter into the beginning of March. Presumably, the extended presence of PSCs provided an aerosol surface for the heterogeneous conversion of CION02 to active chlorine. Assuming most of the available chlorine reacted with ozone, this explains the high CIO concentrations late in the 1996 winter. Thus, the prolonged presence of PSCs is most likely responsible for the observed ozone losses in 1996.
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