On the relationship between the quasi‐biennial oscillation, total chlorine and the severity of the antarctic ozone hole

• Published in: Quarterly Journal of the Royal Meteorological Society
• Main Authors: Butchart, Neal, Austin, John
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1996
• Subjects: Antarctic; Austral; The Antarctic; Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1002/qj.49712252908; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49712252908; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49712252908

Abstract A 3‐dimensional model of the dynamics and radiation of the stratosphere and mesosphere is used to simulate austral spring conditions. An idealized representation of the southern hemisphere planetary waves is prescribed at the 316 mb model lower boundary, and the tropical zonal winds are relaxed towards an idealized time‐dependent representation of the quasi‐biennial oscillation (QBO). As the initial phase of the QBO is changed, the October mean lower‐stratospheric temperatures polewards of 75°S respond systematically, with the two extreme responses found for phases only 1/4 cycle apart rather than for opposite phases. The integrations are repeated for these two phases but with fully interactive photochemistry and different levels of chlorine, corresponding to conditions in about 1980, the mid to late 1980s, and those anticipated in about the year 2010. Increasing the chlorine amount produced systematically deeper ozone holes with areas significantly larger for conditions in the year 2010 than for those in the late 1980s, broadly in agreement with the secular trend observed by the Total Ozone Mapping Spectrometer. For the QBO phase giving lowest temperatures the simulated ozone holes are consistently deeper but with reduced sensitivity for high chlorine amounts. Differences in polar ozone amounts between the two phases are comparable with the observed interannual variability. In the model the results show that the QBO modulates the severity of the antarctic ozone hole directly through the wave‐induced transporting circulation rather than indirectly through the temperature‐dependent heterogeneous chemistry. Further, it is argued that the phases of the QBO producing the two extreme responses in the springtime ozone amounts over Antarctica are likely to depend, in reality, on details of the tropospheric planetary‐wave flux. The model results are also shown to be consistent with the observed downward trend in October antarctic temperatures since 1979.