Atmos. Chem. Phys. Discuss., 7, 7137-7169, 2007
www.atmos-chem-phys-discuss.net/7/7137/2007/
doi:10.5194/acpd-7-7137-2007
© Author(s) 2007. This work is licensed under the
Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
The 1985 southern hemisphere mid-latitude total column ozone anomaly
G. E. Bodeker1, H. Garny2, D. Smale1, M. Dameris3, and R. Deckert3
1National Institute of Water and Atmospheric Research, Lauder, New Zealand
2Meteorological Institute, University of Munich, Munich, Germany
3DLR-Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany

Abstract. One of the most significant events in the evolution of the ozone layer over southern mid-latitudes since the late 1970s was the large decrease observed in 1985. This event remains unexplained and most state-of-the-art atmospheric chemistry-transport models are unable to reproduce it. In this study, the 1985 southern hemisphere mid-latitude total column ozone anomaly is analyzed in detail based on observed daily total column ozone fields, stratospheric dynamical fields, and calculated diagnostics of stratospheric mixing. The 1985 anomaly appears to result from a combination of (i) an anomaly in the meridional circulation resulting from the westerly phase of the equatorial quasi-biennial oscillation (QBO), (ii) weaker transport of ozone from its tropical mid-stratosphere source across the sub-tropical barrier to mid-latitudes related to the particular phasing of the QBO with respect to the annual cycle, and (iii) a solar cycle induced local reduction in ozone. The results based on observations are compared and contrasted with analyses of ozone and dynamical fields from the ECHAM4.L39(DLR)/CHEM coupled chemistry-climate model (hereafter referred to as E39C). Equatorial winds in the E39C model are nudged towards observed winds between 10° S and 10° N and the ability of this model to produce an ozone anomaly in 1985, similar to that observed, confirms the role of the QBO in the anomaly.

Citation: Bodeker, G. E., Garny, H., Smale, D., Dameris, M., and Deckert, R.: The 1985 southern hemisphere mid-latitude total column ozone anomaly, Atmos. Chem. Phys. Discuss., 7, 7137-7169, doi:10.5194/acpd-7-7137-2007, 2007.
 
Search ACPD
Discussion Paper
    XML
    Citation
    Final Revised Paper
    Share