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| Titel |
Influence of grid aspect ratio on planetary boundary layer turbulence in large-eddy simulations |
| VerfasserIn |
S. Nishizawa, H. Yashiro, Y. Sato, Y. Miyamoto, H. Tomita |
| 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. 10 ; Nr. 8, no. 10 (2015-10-28), S.3393-3419 |
| Datensatznummer |
250116614
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| Publikation (Nr.) |
 copernicus.org/gmd-8-3393-2015.pdf |
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| Zusammenfassung |
| We examine the influence of the grid aspect ratio of horizontal to
vertical grid spacing on turbulence in the planetary boundary layer
(PBL) in a large-eddy simulation (LES). In order to clarify
and distinguish them from other artificial effects caused by
numerical schemes, we used a fully compressible meteorological LES
model with a fully explicit scheme of temporal integration. The
influences are investigated with a series of sensitivity tests with
parameter sweeps of spatial resolution and grid aspect ratio. We
confirmed that the mixing length of the eddy viscosity and diffusion
due to sub-grid-scale turbulence plays an essential role in
reproducing the theoretical −5/3 slope of the energy spectrum. If
we define the filter length in LES modeling based on consideration
of the numerical scheme, and introduce a corrective factor for the
grid aspect ratio into the mixing length, the theoretical slope of
the energy spectrum can be obtained; otherwise, spurious energy
piling appears at high wave numbers. We also found that the grid
aspect ratio has influence on the turbulent statistics, especially
the skewness of the vertical velocity near the top of the PBL, which
becomes spuriously large with large aspect ratio, even if
a reasonable spectrum is obtained. |
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