A Simple Shelf Circulation Model: Intrusion of Atlantic Water on the West Spitsbergen Shelf

Barotropic flow along depth contours is found in accordance with standard geostrophic theory. A numerical model is developed that studies the deviation from such a flow. The model gives a good approximation of the dynamical processes on the West Spitsbergen Shelf (WSS) and shows that the West Spitsb...

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Bibliographic Details
Published in:Journal of Physical Oceanography
Main Authors: Nilsen, Frank, Skogseth, Ragnheid, Vaardal-Lunde, Juni, Inall, Mark
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
Upwelling/downwelling
Barotropic flows
Geographic location/entity
Atmosphere-ocean interaction
Models and modeling
Circulation/ Dynamics
Topographic effects
Quasigeostrophic models
Arctic
Arctic Ocean
Spitsbergen Trough
Fram Strait
Isfjord*
Isfjorden
Sea ice
Spitsbergen
Online Access:https://pure.uhi.ac.uk/en/publications/f898bd96-4c03-4e04-8244-cce00e738a49
https://doi.org/10.1175/JPO-D-15-0058.1
https://pureadmin.uhi.ac.uk/ws/files/1963315/Nilsen_et_al_jpo_2016.pdf
Description
Summary:Barotropic flow along depth contours is found in accordance with standard geostrophic theory. A numerical model is developed that studies the deviation from such a flow. The model gives a good approximation of the dynamical processes on the West Spitsbergen Shelf (WSS) and shows that the West Spitsbergen Current (WSC), the main gateway of Atlantic water (AW) toward the Arctic, connects more easily to the Isfjorden Trough than anywhere else along the shelf. The circulation of AW in the troughs along the WSS is here named the Spitsbergen Trough Current (STC). From hydrographical and ocean current observations it is evident that the STC is primarily barotropic and driven by the sea surface height. A connection between the along-coast wind stress and the STC is established, and it is demonstrated how the increased occurrence of winter cyclones in Fram Strait during January–February accelerates and widens the WSC. Ultimately, this results in a strengthened STC and dominance of AW on the WSS. The STC represents a slower route of AW toward the Arctic Ocean and a large heat transport toward the West Spitsbergen fjords during winter (0.2–0.4 TW toward Isfjorden). Heat flux estimates show that half of the AW heat loss in the Isfjorden Trough is due to heat loss to the surrounding water masses, while the rest is lost to the atmosphere. Sea ice production along West Spitsbergen has been reduced, or even nonexistent, in some fjords since 2006. Here, the authors argue that this is a consequence of the strong southerly wind periods along the WSS during winter.

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