Unequivocal Confirmation of the Onset of Stratospheric Ozone Recovery in the Antarctic Ozone Hole

In this paper we evaluate the long-term changes in ozone depletion within the Antarctic ozone hole using a 37 years (1979-2015) of average daily Ozone Mass Deficits (OMD). Excluding PSC-limited years, the 1979-2015 time series of spatially-integrated daily OMD correlates very well with long-term changes in EESC (R2 = 0.89). We find a corresponding statistically highly significant post year-2000 decrease in OMD of -0.77 ± 0.17 Mt (trend significance of 9.8σ), with an associated post year-200 change in OMD of approximately -30 %, consistent with the post year-2000 change in EESC relative to 1980 EESC levels of approximately -30%. The post-year 2000 trend significance is robust to the choice of start year.
The spatial distribution of OMD trends reveals a vortex-core region largely unaffected by dynamics with a post year-2000 trend significance of > 8σ. The vortex-edge region is locally strongly affected by vortex dynamics, but for the vortex-edge region as whole the post year-2000 OMD trend (significance > 9σ) is also unaffected by vortex dynamics. In addition, we do not find evidence for long-term changes in vortex mixing, pre-ozone hole conditions, or the applied assimilation method, playing a role.
Our observation-based results suggest the post year-2000 statistically high significant decrease in OMD is dominated by the long-term decrease in ozone depleting substances and provides the best and most robust evidence to date of Antarctic stratospheric ozone recovery caused by the long-term decrease in ozone depleting substances since 2000 following international emission regulations.