What role does the Antarctic polar vortex play in ozone depletion?

The Antarctic polar vortex plays a critical role in ozone depletion by effectively isolating the air over Antarctica from the rest of the atmosphere. Bounded by a strong stratospheric jet of wind, this vortex prevents the mixing of warmer, ozone-rich air from outside the region with the extremely cold air trapped inside.12

This isolation is essential for the formation of polar stratospheric clouds (PSCs), which occur only at the very low temperatures maintained within the vortex during the polar winter. These clouds provide a surface for chemical reactions that convert less-reactive chlorine-containing molecules into highly reactive forms, such as molecular chlorine.12

When sunlight returns to the Antarctic in the spring, it breaks these accumulated chlorine molecules into single chlorine atoms. These atoms then engage in catalytic cycles that rapidly destroy ozone molecules. This destructive process continues until the polar vortex breaks up, typically in November, allowing the ozone-depleted air to mix with the surrounding atmosphere.1