Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 26, 1207-1220, 2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.
28 May 2008
Ozone trends at northern mid- and high latitudes – a European perspective
N. R. P. Harris1,12, E. Kyrö2, J. Staehelin3, D. Brunner4, S.-B. Andersen5,*, S. Godin-Beekmann6, S. Dhomse7, P. Hadjinicolaou8,9, G. Hansen10, I. Isaksen11, A. Jrrar12,**, A. Karpetchko2, R. Kivi2, B. Knudsen5, P. Krizan13, J. Lastovicka13, J. Maeder3, Y. Orsolini10, J. A. Pyle12, M. Rex14, K. Vanicek15, M. Weber7, I. Wohltmann14, P. Zanis16, and C. Zerefos8 1European Ozone Research Coordinating Unit, University of Cambridge, UK
2Arctic Research Centre of Finnish Meteorological Institute, Sodankylä, Finland
3Swiss Federal Institute of Technology, Zurich, Switzerland
4Empa, Swiss Federal Laboratories for Materials Testing and Research, Dübendorf, Switzerland
5Danish Meteorological Institute, Copenhagen, Denmark
6CNRS-Service d'Aéronomie, Université Pierre et Marie Curie, Paris, France
7University of Bremen, Bremen, Germany
8National and Kapodistrian University of Athens, Greece
9Frederick Institute of Technology, Nicosia, Cyprus
10Norwegian Institute for Air Research, Norway
11University of Oslo, Oslo, Norway
12Centre for Atmospheric Science, University of Cambridge, UK
13Institute of Atmospheric Physics, Academy of the Sciences of the Czech Republic
14Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany
15Czech Hydrometeorological Institute, Czech Republic
16Department of Meteorology – Climatology, Aristotle University of Thessaloniki, Thessaloniki, Greece
*now at: the Danish and Greenlandic Survey, Copenhagen, Denmark
**now at: British Antarctic Survey, Cambridge, UK
Abstract. The EU CANDIDOZ project investigated the chemical and dynamical influences on decadal ozone trends focusing on the Northern Hemisphere. High quality long-term ozone data sets, satellite-based as well as ground-based, and the long-term meteorological reanalyses from ECMWF and NCEP are used together with advanced multiple regression models and atmospheric models to assess the relative roles of chemistry and transport in stratospheric ozone changes. This overall synthesis of the individual analyses in CANDIDOZ shows clearly one common feature in the NH mid latitudes and in the Arctic: an almost monotonic negative trend from the late 1970s to the mid 1990s followed by an increase. In most trend studies, the Equivalent Effective Stratospheric Chlorine (EESC) which peaked in 1997 as a consequence of the Montreal Protocol was observed to describe ozone loss better than a simple linear trend. Furthermore, all individual analyses point to changes in dynamical drivers, such as the residual circulation (responsible for the meridional transport of ozone into middle and high latitudes) playing a key role in the observed turnaround. The changes in ozone transport are associated with variations in polar chemical ozone loss via heterogeneous ozone chemistry on PSCs (polar stratospheric clouds). Synoptic scale processes as represented by the new equivalent latitude proxy, by conventional tropopause altitude or by 250 hPa geopotential height have also been successfully linked to the recent ozone increases in the lowermost stratosphere. These show significant regional variation with a large impact over Europe and seem to be linked to changes in tropospheric climate patterns such as the North Atlantic Oscillation. Some influence in recent ozone increases was also attributed to the rise in solar cycle number 23. Changes from the late 1970s to the mid 1990s were found in a number of characteristics of the Arctic vortex. However, only one trend was found when more recent years are also considered, namely the tendency for cold winters to become colder.

Citation: Harris, N. R. P., Kyrö, E., Staehelin, J., Brunner, D., Andersen, S.-B., Godin-Beekmann, S., Dhomse, S., Hadjinicolaou, P., Hansen, G., Isaksen, I., Jrrar, A., Karpetchko, A., Kivi, R., Knudsen, B., Krizan, P., Lastovicka, J., Maeder, J., Orsolini, Y., Pyle, J. A., Rex, M., Vanicek, K., Weber, M., Wohltmann, I., Zanis, P., and Zerefos, C.: Ozone trends at northern mid- and high latitudes – a European perspective, Ann. Geophys., 26, 1207-1220,, 2008.
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