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Ann. Geophys., 26, 1275-1286, 2008
www.ann-geophys.net/26/1275/2008/
© European Geosciences Union 2008
Longitude-dependent decadal ozone changes and ozone trends in boreal winter months during 1960–2000
D. H. W. Peters, A. Gabriel, and G. Entzian
Leibniz-Institute for Atmospheric Physics at the University of Rostock, Kühlungsborn, Mecklenburg, Germany
Abstract. This study examines the longitude-dependent decadal changes and trends of
ozone for the boreal winter months during the period of 1960–2000. These changes
are caused primarily by changes in the planetary wave structure in the upper
troposphere and lower stratosphere. The decadal changes and trends over 4
decades of geopotential perturbations, defined as a deviation from the zonal
mean, are estimated by linear regression with time. The decadal changes in
longitude-dependent ozone were calculated with a simple transport model of
ozone based on the known planetary wave structure changes and prescribed
zonal mean ozone gradients.
For December of the 1960s and 1980s a statistically significant Rossby
wave track appeared over the North Atlantic and Europe with an anticyclonic
disturbance over the Eastern North Atlantic and Western Europe, flanked by
cyclonic disturbances. In the 1970s and 1990s statistically significant
cyclonic disturbances appeared over the Eastern North Atlantic and Europe,
surrounded by anticyclonic anomalies over Northern Africa, Central Asia and
Greenland. Similar patterns have been found for January. The Rossby wave
track over the North Atlantic and Europe is stronger in the 1980s than in
the 1960s. For February, the variability of the regression patterns is
higher. For January we found a strong alteration in the modelled decadal
changes in total ozone over Central and Northern Europe, showing a decrease
of about 15 DU in the 1960s and 1980s and an increase of about 10 DU in
the 1970s and 1990s.
Over Central Europe the positive geopotential height trend (increase of 2.3 m/yr)
over 40 years is of the same order (about 100 m) as the increase in
the 1980s alone. This is important to recognize because it implies a total
ozone decrease over Europe of the order of 14 DU for the 1960–2000 period,
for January, if we use the standard change regression relation that about a 10-m
geopotential height increase at 300 hPa is related to about a 1.4-DU total
ozone decrease.
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