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| Titel |
Ozone trends at northern mid- and high latitudes – a European perspective |
| VerfasserIn |
N. R. P. Harris, E. Kyrö, J. Staehelin, D. Brunner, S.-B. Andersen, S. Godin-Beekmann, S. Dhomse, P. Hadjinicolaou, G. Hansen, I. Isaksen, A. Jrrar, A. Karpetchko, R. Kivi, B. Knudsen, P. Križan, J. Laštovička, J. Maeder, Y. Orsolini, J. A. Pyle, M. Rex, K. Vanicek, M. Weber, I. Wohltmann, P. Zanis, C. Zerefos |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 26, no. 5 ; Nr. 26, no. 5 (2008-05-28), S.1207-1220 |
| Datensatznummer |
250016096
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| Publikation (Nr.) |
 copernicus.org/angeo-26-1207-2008.pdf |
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| Zusammenfassung |
| 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. |
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