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| Titel |
Is stratospheric air getting younger with time? |
| VerfasserIn |
Beatriz Monge-Sanz, Martyn Chipperfield, Dick Dee, Adrian Simmons, Gabriele Stiller |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097123
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| Publikation (Nr.) |
 EGU/EGU2014-12671.pdf |
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| Zusammenfassung |
| Most climate models have predicted that with the increase in greenhouse gases
concentrations, the stratospheric circulation will intensify, showing younger age-of-air (AoA)
values in this region (e.g. Butchart et al., 2010; WMO, 2011). However, balloon and satellite
observations do not agree with the widespread modelled trend towards younger age-of-air
(Engel et al., 2009; Stiller et al., 2012). To increase our confidence in climate-chemistry
projections, the causes for the apparent age-of-air disagreement between observations and
most models need to be identified.
Here we have carried out stratospheric simulations with a chemistry transport model
(CTM) to evaluate the stratospheric circulation with the ERA-Interim dataset produced by the
European Centre for Medium-Range Weather Forecasts (ECMWF).
The ERA-Interim reanalysis provides age-of-air (AoA) distributions in very good
agreement with observations in the lower stratosphere. Given this agreement, we have used
our simulations to quantify interannual variability and trends in the stratospheric AoA for the
whole ERA-Interim period (1979-present).
Our model results with ERA-Interim fields disagree with the decreasing tendency in
age-of-air widespread in most models, but are in good agreement with the recent age-of-air
studies based on observations. To explore potential causes for the AoA trends in our model,
Lagrangian calculations are also performed to assess mixing processes for the ERA-Interim
period. Potential links between our modelled AoA trends and stratospheric ozone evolution
are also shown.
References:
Butchart, et al., 2010. J. Climate, 23, 5349–5374, doi:10.1175/2010JCLI3404.1.
Engel et al., 2009. Nat. Geosci. 2: 28–31, doi:10.1038/ngeo388.
Stiller et al., 2012. Atmos. Chem. Phys. 12: 3311–3331, doi:10.5194/acp–12–3311–2012.
WMO. 2011. Global Ozone Research and Monitoring Project -Report No. 52. |
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