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| Titel |
Meteorological implementation issues in chemistry and transport models |
| VerfasserIn |
S. E. Strahan, B. C. Polansky |
| 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 ; 6, no. 10 ; Nr. 6, no. 10 (2006-07-12), S.2895-2910 |
| Datensatznummer |
250004006
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| Publikation (Nr.) |
 copernicus.org/acp-6-2895-2006.pdf |
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| Zusammenfassung |
| Offline chemistry and transport models (CTMs) are
versatile tools for studying composition and climate issues requiring
multi-decadal simulations. They are computationally fast compared to coupled
chemistry climate models, making them well-suited for integrating
sensitivity experiments necessary for understanding model performance and
interpreting results. The archived meteorological fields used by CTMs can be
implemented with lower horizontal or vertical resolution than the original
meteorological fields in order to shorten integration time, but the effects
of these shortcuts on transport processes must be understood if the CTM is
to have credibility. In this paper we present a series of sensitivity
experiments on a CTM using the Lin and Rood advection scheme, each differing
from another by a single feature of the wind field implementation. Transport
effects arising from changes in resolution and model lid height are
evaluated using process-oriented diagnostics that intercompare CH4,
O3, and age tracer carried in the simulations. Some of the diagnostics
used are derived from observations and are shown as a reality check for the
model. Processes evaluated include tropical ascent, tropical-midlatitude
exchange, poleward circulation in the upper stratosphere, and the
development of the Antarctic vortex. We find that faithful representation of
stratospheric transport in this CTM is possible with a full mesosphere,
~1 km resolution in the lower stratosphere, and relatively low
vertical resolution (>4 km spacing) in the middle stratosphere and above,
but lowering the lid from the upper to lower mesosphere leads to less
realistic constituent distributions in the upper stratosphere. Ultimately,
this affects the polar lower stratosphere, but the effects are greater for
the Antarctic than the Arctic. The fidelity of lower stratospheric transport
requires realistic tropical and high latitude mixing barriers which are
produced at 2°×2.5°, but not lower resolution. At
2°×2.5° resolution, the CTM produces a vortex capable of isolating
perturbed chemistry (e.g. high Cly and low NOy) required for
simulating polar ozone loss. |
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