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Titel |
Revision of the convective transport module CVTRANS 2.4 in the EMAC atmospheric chemistry–climate model |
VerfasserIn |
H. G. Ouwersloot, A. Pozzer, B. Steil, H. Tost, J. Lelieveld |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1991-959X
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Digitales Dokument |
URL |
Erschienen |
In: Geoscientific Model Development ; 8, no. 8 ; Nr. 8, no. 8 (2015-08-05), S.2435-2445 |
Datensatznummer |
250116501
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Publikation (Nr.) |
copernicus.org/gmd-8-2435-2015.pdf |
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Zusammenfassung |
The convective transport module, CVTRANS, of the ECHAM/MESSy
Atmospheric Chemistry (EMAC) model has been revised to better
represent the physical flows and incorporate recent findings on the
properties of the convective plumes. The modifications involve
(i) applying intermediate time stepping based on a settable
criterion, (ii) using an analytic expression to account for the
intra-time-step mixing ratio evolution below cloud base, and
(iii) implementing a novel expression for the mixing ratios of atmospheric
compounds at the base of an updraft. Even when averaged over
a year, the predicted mixing ratios of atmospheric compounds are
affected considerably by the intermediate time stepping. For
example, for an exponentially decaying atmospheric tracer with
a lifetime of 1 day, the zonal averages can locally differ by more
than a factor of 6 and the induced root mean square deviation from
the original code is, weighted by the air mass, higher than 40 %
of the average mixing ratio. The other modifications result in
smaller differences. However, since they do not require additional
computational time, their application is also recommended. |
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