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| Titel |
Long-range transport of terrain-induced turbulence from high-resolution numerical simulations |
| VerfasserIn |
M. Katurji, S. Zhong, P. Zawar-Reza |
| 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 ; 11, no. 22 ; Nr. 11, no. 22 (2011-11-25), S.11793-11805 |
| Datensatznummer |
250010221
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| Publikation (Nr.) |
 copernicus.org/acp-11-11793-2011.pdf |
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| Zusammenfassung |
| Over complex terrain, an important question is how various topographic
features may generate or alter wind turbulence and how far the influence can
be extended downstream. Current measurement technology limits the capability
in providing a long-range snapshot of turbulence as atmospheric eddies
travel over terrain, interact with each other, change their productive and
dissipative properties, and are then observed tens of kilometers downstream
of their source. In this study, we investigate through high-resolution
numerical simulations the atmospheric transport of terrain-generated
turbulence in an atmosphere that is neutrally stratified. The simulations
are two-dimensional with an isotropic spatial resolution of 15 m and run to
a quasi-steady state. They are designed in such a way to allow an
examination of the effects of a bell-shaped experimental hill with varying
height and aspect ratio on turbulence properties generated by another hill
20 km upstream. Averaged fields of the turbulent kinetic energy (TKE) imply
that terrain could have a large influence on velocity perturbations at least
30H (H is the terrain height) upstream and downstream of the terrain, with the
largest effect happening in the area of the largest pressure perturbations.
The results also show that downstream of the terrain the TKE fields are
sensitive to the terrain's aspect ratio with larger enhancement in
turbulence by higher aspect ratio, while upstream there is a suppression of
turbulence that does not appear to be sensitive to the terrain aspect ratio.
Instantaneous vorticity fields shows very detailed flow structures that
resemble a multitude of eddy scales dynamically interacting while shearing
oppositely paired vortices. The knowledge of the turbulence production and
modifications by topography from these high-resolution simulations can be
helpful in understanding long-range terrain-induced turbulence and improving
turbulence parameterizations used in lower resolution weather prediction
models. |
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