Ozone Hole

Yang E.-S., D. M. Cunnold, M. J. Newchurch, R. J. Salawitch, M. P. McCormick, J. M. Russell III, J. M. Zawodny, S. J. Oltmans (2008), First stage of Antarctic ozone recovery, J. Geophys. Res., 113, D20308, doi:10.1029/2007JD009675.Full Text

Correlations between monthly means of total ozone columns and temperatures in the vortex core and the vortex edge regions are used to construct ozone anomaly time series for September and October.

The ozone anomaly time series reveal a statistically significant leveling off of total ozone, relative to the previous rate of decline, since 1997.

The second derivative with respect to time of stratospheric halogen loading in the Antarctic vortex reached a well-defined minimum in 1997, marking the time when the chemical forcing of polar ozone loss started leveling off.

Total column ozone within the Antarctic vortex core and collar regions has reached the first stage of recovery as defined by the World Meteorological Organization: a statistically significant reduction in the rate of decline that is clearly attributable to decreases in the abundance of ozone-depleting substances brought about by the Montreal Protocol.