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| Titel |
Quantifying the contributions to stratospheric ozone changes from ozone depleting substances and greenhouse gases |
| VerfasserIn |
D. A. Plummer, J. F. Scinocca, T. G. Shepherd, M. C. Reader, A. I. Jonsson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 18 ; Nr. 10, no. 18 (2010-09-20), S.8803-8820 |
| Datensatznummer |
250008780
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| Publikation (Nr.) |
 copernicus.org/acp-10-8803-2010.pdf |
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| Zusammenfassung |
| A state-of-the-art chemistry climate model coupled to a three-dimensional ocean
model is used to produce three experiments, all seamlessly covering the period
1950–2100, forced by different combinations of long-lived Greenhouse Gases (GHGs)
and Ozone Depleting Substances (ODSs). The experiments are designed to quantify the
separate effects of GHGs and ODSs on the evolution of ozone, as well as the extent
to which these effects are independent of each other, by alternately holding one
set of these two forcings constant in combination with a third experiment where
both ODSs and GHGs vary. We estimate that up to the year 2000 the net decrease
in the column amount of ozone above 20 hPa is approximately 75% of the decrease
that can be attributed to ODSs due to the offsetting effects of cooling by
increased CO2. Over the 21st century, as ODSs decrease, continued cooling
from CO2 is projected to account for more than 50% of the projected
increase in ozone above 20 hPa. Changes in ozone below 20 hPa show a
redistribution of ozone from tropical to extra-tropical latitudes with an
increase in the Brewer-Dobson circulation. In addition to a latitudinal
redistribution of ozone, we find that the globally averaged column amount of
ozone below 20 hPa decreases over the 21st century, which significantly
mitigates the effect of upper stratospheric cooling on total column ozone.
Analysis by linear regression shows that the recovery of ozone from the effects
of ODSs generally follows the decline in reactive chlorine and bromine levels,
with the exception of the lower polar stratosphere where recovery of ozone in the
second half of the 21st century is slower than would be indicated by the decline
in reactive chlorine and bromine concentrations. These results also reveal the
degree to which GHG-related effects mute the chemical effects of N2O on ozone
in the standard future scenario used for the WMO Ozone Assessment. Increases in
the residual circulation of the atmosphere and chemical effects from CO2
cooling more than halve the increase in reactive nitrogen in the mid to upper
stratosphere that results from the specified increase in N2O between 1950
and 2100. |
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