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Eddy saturation and frictional control of the Antarctic Circumpolar Current

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  • David P. Marshall
  • Maarten H. P. Ambaum
  • James Maddison
  • David R. Munday
  • Lenka Novak

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    Rights statement: © 2016 American Geophysical Union. All rights reserved.

    Accepted author manuscript, 937 KB, PDF document

Original languageEnglish
Pages (from-to)286-292
Number of pages7
JournalGeophysical Research Letters
Volume44
Issue number1
Early online date21 Dec 2016
DOIs
Publication statusPublished - 28 Jan 2017

Abstract

The Antarctic Circumpolar Current is the strongest current in the ocean and has a pivotal impact on ocean stratification, heat content, and carbon content. The circumpolar volume transport is relatively insensitive to surface wind forcing in models that resolve turbulent ocean eddies, a process termed “eddy saturation.” Here a simple model is presented that explains the physics of eddy saturation with three ingredients: a momentum budget, a relation between the eddy form stress and eddy energy, and an eddy energy budget. The model explains both the insensitivity of circumpolar volume transport to surface wind stress and the increase of eddy energy with wind stress. The model further predicts that circumpolar transport increases with increased bottom friction, a counterintuitive result that is confirmed in eddy-permitting calculations. These results suggest an unexpected and important impact of eddy energy dissipation, through bottom drag or lee wave generation, on ocean stratification, ocean heat content, and potentially atmospheric CO2.

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