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| Titel |
Nonlinear response of modelled stratospheric ozone to changes in greenhouse gases and ozone depleting substances in the recent past |
| VerfasserIn |
S. Meul, S. Oberländer-Hayn, J. Abalichin, U. Langematz |
| 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 ; 15, no. 12 ; Nr. 15, no. 12 (2015-06-24), S.6897-6911 |
| Datensatznummer |
250119848
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| Publikation (Nr.) |
 copernicus.org/acp-15-6897-2015.pdf |
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| Zusammenfassung |
| In the recent past, the evolution of stratospheric ozone (O3) was
affected by both increasing ozone depleting substances (ODSs) and greenhouse
gases (GHGs). The impact of the single forcings on O3 is well known.
Interactions between the simultaneously increased GHG and ODS concentrations,
however, can occur and lead to nonlinear O3 changes. In this study, we
investigate if nonlinear processes have affected O3 changes between 1960
and 2000. This is done with an idealised set of time slice simulations with
the chemistry-climate model EMAC. Due to nonlinearity the past ozone
loss is diminished throughout the stratosphere, with a maximum reduction of
1.2 % at 3 hPa. The total ozone column loss between 1960 and 2000 that is
mainly attributed to the ODS increase is mitigated in the extra-polar regions
by up to 1.1 % due to nonlinear processes. A separation of the O3
changes into the contribution from chemistry and transport shows that
nonlinear interactions occur in both. In the upper stratosphere a reduced
efficiency of the ClOx-catalysed O3 loss chiefly causes the
nonlinear O3 increase. An enhanced formation of halogen reservoir
species through the reaction with methane (CH4) reduces the abundance of
halogen radicals significantly. The temperature-induced deceleration of the
O3 loss reaction rate in the Chapman cycle is reduced, which leads to a
nonlinear O3 decrease and counteracts the increase due to ClOx.
Nonlinear effects on the NOx abundance cause hemispheric asymmetric
nonlinear changes of the O3 loss. Nonlinear changes in O3 transport
occur in particular in the Southern Hemisphere (SH) during the months
September to November. Here, the residual circulation is weakened in the
lower stratosphere, which goes along with a reduced O3 transport from
the tropics to high latitudes. Thus, O3 decreases in the SH polar
region but increases in the SH midlatitudes. The existence of nonlinearities
implies that future ozone change due to ODS decline slightly depends on the
prevailing GHG concentrations. Therefore the future ozone evolution will not
simply be a reversal of the past. |
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