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Generation of a buoyancy-driven coastal current by an Antarctic polynya

Wilchinsky, AV; Feltham, DL; (2008) Generation of a buoyancy-driven coastal current by an Antarctic polynya. J PHYS OCEANOGR , 38 (5) 1011 - 1032. 10.1175/2007JPO3831.1.

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Abstract

Descent and spreading of high salinity water generated by salt rejection during sea ice formation in an Antarctic coastal polynya is studied using a hydrostatic, primitive equation three-dimensional ocean model called the Proudman Oceanographic Laboratory Coastal Ocean Modeling System (POLCOMS). The shape of the polynya is assumed to be a rectangle 100 km long and 30 km wide, and the salinity flux into the polynya at its surface is constant. The model has been run at high horizontal spatial resolution (500 m), and numerical simulations reveal a buoyancy-driven coastal current. The coastal current is a robust feature and appears in a range of simulations designed to investigate the influence of a sloping bottom, variable bottom drag, variable vertical turbulent diffusivities, higher salinity flux, and an offshore position of the polynya. It is shown that bottom drag is the main factor determining the current width. This coastal current has not been produced with other numerical models of polynyas, which may be because these models were run at coarser resolutions. The coastal current becomes unstable upstream of its front when the polynya is adjacent to the coast. When the polynya is situated offshore, an unstable current is produced from its outset owing to the capture of cyclonic eddies. The effect of a coastal protrusion and a canyon on the current motion is investigated. In particular, due to the convex shape of the coastal protrusion, the current sheds a dipolar eddy.

Type:Article
Title:Generation of a buoyancy-driven coastal current by an Antarctic polynya
DOI:10.1175/2007JPO3831.1
Keywords:SLOPING CONTINENTAL-SHELF, DENSE WATER, BAROCLINIC INSTABILITY, OFFSHORE TRANSPORT, STRATIFIED FLUID, ROTATING FLUID, MIXED-LAYER, MODEL, OCEAN, BOUNDARY
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences

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