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| Titel |
Structure and forcing of the overflow at the Storfjorden sill and its connection to the Arctic coastal polynya in Storfjorden |
| VerfasserIn |
F. Geyer, I. Fer, L. H. Smedsrud |
| 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 ; 6, no. 1 ; Nr. 6, no. 1 (2010-03-22), S.401-411 |
| Datensatznummer |
250003368
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| Publikation (Nr.) |
 copernicus.org/os-6-401-2010.pdf |
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| Zusammenfassung |
| Storfjorden (Svalbard) is a sill-fjord with an active polynya and exemplifies
the dense water formation process over the Arctic shelves. Here we report on
our simulations of Storfjorden covering the freezing season of 1999–2000
using an eddy-permitting 3-D ocean circulation model with a fully coupled
dynamic and thermodynamic sea-ice model. The model results in the polynya
region and of the dense water plume flowing over the sill crest are compared
to observations. The connections of the overflow at the sill to the dense
water production at the polynya and to the local wind forcing are
investigated. Both the overflow and the polynya dynamics are found to be
sensitive to wind forcing. In response to freezing and brine rejection over
the polynya, the buoyancy forcing initiates an abrupt positive density
anomaly. While the ocean integrates the buoyancy forcing over several polynya
events (about 25 days), the wind forcing dominates the overflow response at
the sill at weather scale. In the model, the density excess is diluted in the
basin and leads to a gradual build-up of dense water behind the sill. The
overflow transport is typically inferred from observations using a single
current profiler at the sill crest. Despite the significant variability of
the plume width, we show that a constant overflow width of 15 km produces
realistic estimates of the overflow volume transport. Another difficulty in
monitoring the overflow is measuring the plume thickness in the absence of
hydrographic profiles. Volume flux estimates assuming a constant plume width
and the thickness inferred from velocity profiles explain 58% of the
modelled overflow volume flux variance and agrees to within 10% when
averaged over the overflow season. |
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