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| Titel |
Turbulent dispersion properties from a model simulation of the western Mediterranean Sea |
| VerfasserIn |
H. Nefzi, D. Elhmaidi, X. Carton |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 10, no. 2 ; Nr. 10, no. 2 (2014-03-14), S.167-175 |
| Datensatznummer |
250116963
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| Publikation (Nr.) |
 copernicus.org/os-10-167-2014.pdf |
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| Zusammenfassung |
Using a high-resolution primitive equation model of the western Mediterranean
Sea, we analyzed the dispersion properties of a set of homogeneously
distributed, passive particle pairs. These particles were initially separated
by different distances D0 (D0 = 5.55, 11.1 and 16.65 km), and were
seeded in the model at initial depths of 44 and 500 m.
This realistic ocean model, which reproduces the main features of the
regional circulation, puts into evidence the three well-known regimes of
relative dispersion.
The first regime due to the chaotic advection at small scales lasts only a
few days (3 days at 44 m depth, a duration comparable with the integral
timescale), and the relative dispersion is then exponential. In the second
regime, extending from 3 to 20 days, the relative dispersion has a power law
tα where α tends to 3 as D0 becomes small. In the
third regime, a linear growth of the relative dispersion is observed starting
from the twentieth day. For the relative diffusivity, the D2 growth is
followed by the Richardson regime D4/3. At large scales, where particle
velocities are decorrelated, the relative diffusivity is constant.
At 500 m depth, the integral timescale increases (> 4 days)
and the intermediate regime becomes narrower than that at 44 m depth due to
the weaker effect of vortices (this effect decreases with depth). The
turbulent properties become less intermittent and more homogeneous and the
Richardson law takes place. |
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