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| Titel |
The analysis of large-scale turbulence characteristics in the Indonesian seas derived from a regional model based on the Princeton Ocean Model |
| VerfasserIn |
K. O'Driscoll, V. Kamenkovich |
| 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 ; 8, no. 4 ; Nr. 8, no. 4 (2012-08-15), S.615-631 |
| Datensatznummer |
250005754
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| Publikation (Nr.) |
 copernicus.org/os-8-615-2012.pdf |
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| Zusammenfassung |
Turbulence characteristics in the Indonesian seas on the horizontal scale of
order of 100 km were calculated with a regional model of the Indonesian seas
circulation in the area based on the Princeton Ocean Model (POM). As is well
known, the POM incorporates the Mellor–Yamada turbulence closure scheme. The
calculated characteristics are: twice the turbulence kinetic energy per unit
mass, q2; the turbulence master scale, ℓ; mixing coefficients of
momentum, KM; and temperature and salinity, KH; etc. The analyzed
turbulence has been generated essentially by the shear of large-scale ocean
currents and by the large-scale wind turbulence. We focused on the analysis
of turbulence around important topographic features, such as the Lifamatola
Sill, the North Sangihe Ridge, the Dewakang Sill, and the North and South
Halmahera Sea Sills. In general, the structure of turbulence characteristics
in these regions turned out to be similar. For this reason, we have carried
out a detailed analysis of the Lifamatola Sill region because dynamically
this region is very important and some estimates of mixing coefficients in
this area are available.
Briefly, the main results are as follows. The distribution of q2 is quite
adequately reproduced by the model. To the north of the Lifamatola Sill (in
the Maluku Sea) and to the south of the Sill (in the Seram Sea), large values
of q2 occur in the deep layer extending several hundred meters above the
bottom. The observed increase of q2 near the very bottom is probably due
to the increase of velocity shear and the corresponding shear production of
q2 very close to the bottom. The turbulence master scale, ℓ, was
found to be constant in the main depth of the ocean, while ℓ rapidly
decreases close to the bottom, as one would expect. However, in deep profiles
away from the sill, the effect of topography results in the ℓ structure
being unreasonably complicated as one moves towards the bottom. Values of 15
to 20 × 10−4 m2 s−1 were obtained for KM and KH in deep
water in the vicinity of the Lifamatola Sill. These estimates agree well with
basin-scale averaged values of 13.3 × 10−4 m2 s−1 found
diagnostically for KH in the deep Banda and Seram Seas
(Gordon et al., 2003) and a value of 9.0 × 10−4 m2 s−1 found
diagnostically for KH for the deep Banda Sea system
(van Aken et al., 1988). The somewhat higher simulated values can be
explained by the presence of steep topography around the sill. |
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