Twenty-two years of ozonesonde measurements at the South Pole

Since 1986, the Earth System Research Laboratory and its predecessors have been making weekly balloon ozone soundings at the South Pole Station in Antarctica. During the springtime ozone hole period, the sounding frequency is increased to 2–3 per week. The 2007 springtime minimum total column ozone at South Pole was 125 Dobson units, with the layer between 14 and 21 km showing a typical 95% loss of ozone. In contrast, the 2006 minimum total column ozone was 93 Dobson units and showed 99% ozone destruction in the 14–21 km layer. Owing to variations in meteorology and stability of the polar vortex, year to year variations in the severity of the ozone hole of this magnitude are expected. Analysis of the ozone loss rate in September indicates large interannual variability suggesting a dynamic component. Detailed analysis of the 22-year record is used to search for early signs of the beginning of ozone hole recovery. The conclusion is that up to the year 2007, no definitive signs of the beginning of ozone hole recovery have been detected at South Pole Station.