Atmospheric Chemistry and Physics Discussions Future Antarctic ozone recovery rates in September–December predicted by CCMVal-2 model simulations

Abstract

Chemistry-climate model validation phase 2 (CCMVal-2) model simulations are used to analyze Antarctic ozone recovery rates in 2000–2100 during local spring and early summer, both vertically integrated and at several pressure levels in the lower strato-sphere. Multi-model median trends of monthly zonal mean total ozone column (TOC), 5 ozone volume mixing ratio (VMR), wind speed and temperature poleward of 60 • S are investigated. Median values are used to account for large variability in models, and the associated uncertainty is calculated using a bootstrapping technique. According to the selected ten CCMVal-2 models, Antarctic TOC will return to its pre-ozone hole level, taken as an average of 1970–1979 values, between 2065 and 2075 in September– 10 November, and around 2050 in December. In 2000–2020, an increase in TOC is much smaller than in later years, and this is especially evident for December. Although the December TOC recovers to its pre-ozone hole levels earlier compared to all spring months (as the December ozone depletion was much lower), the rate of December TOC increase, is slower than that for all spring months. Projected trends in ozone 15 VMR, temperature and winds at several pressure levels are analyzed in order to at-tribute the projected rate of December TOC recovery, as well as to investigate future changes in the Antarctic atmosphere in general, including some aspects of the polar vortex breakup.