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| Titel |
Mixing and transformation in the Denmark Strait Overflow |
| VerfasserIn |
Inga Koszalka, Thomas Haine, Marcello Magaldi |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097074
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| Publikation (Nr.) |
 EGU/EGU2014-12618.pdf |
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| Zusammenfassung |
| The Denmark Strait Overflow (DSO) is one of the major export routes for the dense waters
from the Nordic Seas to the North Atlantic. However, the observations of the DSO are limited
to a few locations and poorly resolve mixing processes that transform the dense waters
and hence influence propagation of hydrographic signals from the Arctic to the
Atlantic.
We use a high resolution circulation model to diagnose mixing processes involving the
DSO in the Irminger Basin. We focus on mesoscale (10-100km) processes, the most
prominent being dense cyclonic boluses making up the overflow plume. The subgrid
turbulent processes are represented by the K-profile parameterization. We map the horizontal
and vertical eddy diffusivities derived from Lagrangian particles, the model vertical mixing
coefficient and eddy fluxes. Our results are consistent with observations suggesting enhanced
vertical mixing during the initial (~ 200km) descent of the dense plume and increasing
importance of horizontal mixing downstream. The model also shows enhanced
mixing along the dense water pathways in the Kangerdlugssuaq Trough on the East
Greenland Shelf involving fresh Polar Waters. However, the most intense mixing
is induced by mesoscale boluses of dense water cascading down the sill and the
associated internal wave field. Frequent occurrence of a neutrally stratified mixed
layer in the dense plume poses a challenge for the turbulent scheme of the model.
We advocate for an observational campaign that would corroborate these results
and help develop novel parametrizations of the vertical mixing processes in the
DSO. |
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