A new tool for the study of the ozone hole dynamics over Antarctica

An analysis of the time series of the maximum daily ozone hole area over Antarctica for each year during the period 1979–2009 is presented, based on the entropy S defined in a new time domain termed natural time domain, that captures characteristics of the dynamics of the ozone hole complex system. The results obtained show that the entropy in natural time for scales 3–7 years and its value under time reversal for all scales (3–15 years) almost stabilizes during the last several years. On the other hand, characteristic features of this entropy are clearly found before the unprecedented event of the major, sudden stratospheric warming and the subsequent break-up of the Antarctic ozone hole into two holes in September 2002. In particular, the following precursory changes have been identified: First, for scales larger than 8 years, the entropy in natural time exhibits a gradual increase after around 1999. Second, from 2000 to 2001, the entropy in natural time under time reversal shows an increase for all scales (3–15 years) except for the scale of 13 years. Third, the values of the entropy change in natural time almost coincide at 2000 for the short scales 3–7 years and then decrease. The analysis in the natural time domain is also applied on the eddy heat flux, which is proportional to the vertically propagating wave activity affecting the ozone hole over Antarctica. The results drawn confirm those deduced from the ozone hole area diagnostics.

► We study the dynamical evolution of the Antarctic ozone hole with a new tool.
► We make use of the entropy defined in a new time domain termed natural time domain.
► Precursory changes found before the ozone hole split over Antarctica in 2002.