Establishment of momentum balance by form stress in a wind-driven channel
Date
2011
Authors
Ward, Marshall
Hogg, Andrew
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Publisher
Elsevier
Abstract
We examine the establishment of form stress in the spinup of a rotating isopycnal wind-driven channel model, with reference to the Antarctic Circumpolar Current. Initially, the force balance resembles Ekman layer transport, where zonal surface winds are balanced by the Coriolis forces in the upper layers, while the bottom layers consist of an opposing meridional flow balanced by topographic form stress. As the meridional transport increases, the isopycnal slopes and zonal transport also increase and the flow becomes baroclinically unstable, leading to the development of interfacial form stresses due to small-scale baroclinic eddies. This form stress alters the force balance of the layers, causing the system to geostrophically readjust to new states with progressively lower meridional transports. This trend continues until the meridional transport stops and the current is balanced solely by winds and form stress. The final state is a turbulent flow consisting of a several meandering jets that are maintained by the mesoscale eddy field. Our results resemble recent observations of the Antarctic Circumpolar Current and illustrate the contribution of mesoscale eddies to the force balance of the Southern Ocean.
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Keywords
Keywords: Antarctic Circumpolar Currents; Baroclinic eddy; Bottom layers; Channel model; Ekman layers; Ekman transport; Final state; Force balances; Meridional flows; Meridional transport; Mesoscale eddy; Mesoscale eddy fields; Modelling; Momentum balances; Souther Channel flow; Ekman transport; Mesoscale eddies; Modelling; Momentum transfer; Wind-driven currents
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Source
Ocean Modelling
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Journal article
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2037-12-31
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