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| Titel |
Descent and mixing of the overflow plume from Storfjord in Svalbard: an idealized numerical model study |
| VerfasserIn |
I. Fer, B. Ådlandsvik |
| 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 ; 4, no. 2 ; Nr. 4, no. 2 (2008-05-06), S.115-132 |
| Datensatznummer |
250001639
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| Publikation (Nr.) |
 copernicus.org/os-4-115-2008.pdf |
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| Zusammenfassung |
| Storfjorden in the Svalbard Archipelago is a sill-fjord that produces
significant volumes of dense, brine-enriched shelf water through ice
formation. The dense water produced in the fjord overflows the sill and can
reach deep into the Fram Strait. For conditions corresponding to a moderate
ice production year, the pathway of the overflow, its descent and evolving
water mass properties due to mixing are investigated for the first time
using a high resolution 3-D numerical model. An idealized modeling approach
forced by a typical annual cycle of buoyancy forcing due to ice production
is chosen in a terrain-following vertical co-ordinate. Comparison with
observational data, including hydrography, fine resolution current
measurements and direct turbulence measurements using a microstructure
profiler, gives confidence on the model performance. The model eddy diffusivity
profiles contrasted to those inferred from the turbulence measurements give
confidence on the skill of the Mellor Yamada scheme in representing sub-grid
scale mixing for the Storfjorden overflow, and probably for gravity current
modeling, in general. The Storfjorden overflow is characterized by low
Froude number dynamics except at the shelf break where the plume narrows,
accelerates with speed reaching 0.6 m s−1, yielding local Froude
number in excess of unity. The volume flux of the plume increases by
five-fold from the sill to downstream of the shelf-break. Rotational
hydraulic control is not applicable for transport estimates at the sill
using upstream basin information. To the leading order, geostrophy
establishes the lateral slope of the plume interface at the sill. This
allows for a transport estimate that is consistent with the model results by
evaluating a weir relation at the sill. |
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