Total ozone during the unusual Antarctic winter of 2002

Abstract

A major stratospheric warming was observed in the southern hemisphere during September 2002 for the first time. Total ozone observations from the Global Ozone Monitoring Experiment (GOME) show the ozone hole dividing into two parts in late September, followed by a reestablishment of the pole centered ozone hole (defined as the area of total ozone below 220 DU) in October. The ozone observations are well reproduced by a chemical transport model (CTM) driven by analyzed wind fields and temperatures. Antarctic total ozone was significantly higher during winter and spring 2002 than during previous years. GOME showed October averages for the area south of 63°S of 291 DU for 2002, compared to between 204 and 248 DU for the years 1995–2001. Comparison with the CTM indicates that the unusually high ozone columns are largely a result of increased transport during the winter 2002. The estimated chemical loss of total ozone of about 80 DU south of 60°S is comparable to that of previous winters. We conclude that the increased total ozone during this winter must not be considered as a sign of ozone recovery but is just a consequence of an unusual meteorological situation during the winter of 2002.