The existence of the edge region of the Antarctic stratospheric vortex

New evidence from models, ozone measurements and balloon trajectories is presented that confirms the existence of a broad cohesive region of air at the edge of the Antarctic stratospheric vortex that is only weakly mixed with the core of the vortex. Comprehensive measurements by Antarctic ozonesondes in 2003 show quite different evolution in the edge region than in the core. With one exception, long duration balloons launched from Antarctica in spring 2005 remained confined to either the edge region of the vortex or its core. Calculations of effective diffusivity for 2003 and 2005 show similarly weak mixing in the edge region as earlier calculations for 1996. They again show that the edge region is a significant proportion of the area of the ozone hole. Its importance lies in the possibility that, unmixed, it can have more polar stratospheric clouds during the course of the 21st century, thereby delaying the recovery of the ozone hole.