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| Titel |
Implications of Lagrangian transport for simulations with a coupled chemistry-climate model |
| VerfasserIn |
A. Stenke, M. Dameris, V. Grewe, H. Garny |
| 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 ; 9, no. 15 ; Nr. 9, no. 15 (2009-08-04), S.5489-5504 |
| Datensatznummer |
250007555
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| Publikation (Nr.) |
 copernicus.org/acp-9-5489-2009.pdf |
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| Zusammenfassung |
| For the first time a purely Lagrangian transport algorithm is
applied in a fully coupled chemistry-climate model (CCM). We use the
numerically non-diffusive Lagrangian scheme ATTILA instead of the
operational semi-Lagrangian scheme for the transport of water
vapour, cloud water and chemical trace species in the CCM E39C. The
new model version including the Lagrangian scheme is referred to as
E39C-A. The implications of the Lagrangian transport scheme for
stratospheric model dynamics and tracer distributions in E39C-A are
evaluated by comparison with observations and results of the
previous model version E39C. We found in a previous paper that
several deficiencies in stratospheric dynamics in E39C originate
from a pronounced modelled wet bias and an associated cold bias in
the extra-tropical lowermost stratosphere. Contrary to the
semi-Lagrangian scheme ATTILA shows a largely reduced meridional
transport of water vapour from the tropical upper troposphere into
the extratropical lowermost stratosphere. The reduction of the
moisture and temperature bias in E39C-A leads to a significant
advancement of stratospheric dynamics in terms of the mean state as
well as annual and interannual variability. In this study we show
that as a consequence of both, the favourable numerical
characteristics of the Lagrangian transport scheme and the improved
model dynamics, E39C-A generally shows more realistic distributions
of chemical trace species: Compared to E39C high stratospheric
chlorine (Cly) concentrations extend further downward.
Therefore E39C-A realistically covers the altitude of maximum ozone
depletion in the stratosphere. The location of the ozonopause,
i.e. the transition from low tropospheric to high stratospheric
ozone values, is also clearly improved in E39C-A. Not only the
spatial distribution but also the temporal evolution of
stratospheric Cly in the past is realistically reproduced in
E39C-A which is an important step towards a more reliable projection
of future changes, especially of stratospheric ozone. Despite a
large number of improvements there are still remaining model
deficiencies like a general overestimation of total column ozone. |
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