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Titel |
Influence of along-valley terrain heterogeneity on exchange processes over idealized valleys |
VerfasserIn |
J. S. Wagner, A. Gohm, M. W. Rotach |
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 (2015-06-16), S.6589-6603 |
Datensatznummer |
250119828
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Publikation (Nr.) |
copernicus.org/acp-15-6589-2015.pdf |
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Zusammenfassung |
Idealized numerical simulations of thermally driven flows over various valley–plain topographies
are performed under daytime conditions. Valley floor inclination and narrowing valley cross sections
are systematically varied to study the influence of along-valley terrain
heterogeneity on the developing boundary layer structure, as well as horizontal and vertical
transport processes. Valley topographies with inclined valley floors of 0.86° increase
upvalley winds by a factor of about 1.9 due to smaller valley volumes (volume effect) and by a
factor of about 1.6
due to additional upslope buoyancy forces. Narrowing the valley cross section by 20 km per
100 km along-valley distance increases upvalley winds by a factor of about 2.6. Vertical mass fluxes out
of the valley are strongly increased by a factor between 1.8 and 2.8 by narrowing the valley cross sections
and by a factor of 1.2 by inclining the valley floor. Trajectory analysis shows
intensified horizontal transport of parcels from the foreland into the valley within the boundary
layer in cases with inclined floors and narrowing cross sections due to increased upvalley winds. |
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