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Circumpolar variations in the chaotic nature of Southern Ocean eddy dynamics
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  • Andrew McC. Hogg,
  • Thierry Penduff,
  • Sally E. Close,
  • William K. Dewar,
  • Navid C Constantinou,
  • Josué Martínez-Moreno
Andrew McC. Hogg
Australian National University

Corresponding Author:[email protected]

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Thierry Penduff
Laboratoire de Glaciologie et Geophysique de l'Environnement, CNRS
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Sally E. Close
Laboratore d'Oceanographie Physique et Spatiale (LOPS), University of Brest/IFREMER/IRD/CNRS
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William K. Dewar
Florida State University
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Navid C Constantinou
Australian National University
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Josué Martínez-Moreno
Australian National University
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Circulation in the Southern Ocean is unique. The strong wind stress forcing and buoyancy fluxes, in concert with the lack of continental boundaries, conspire to drive the Antarctic Circumpolar Current replete with an intense eddy field. The effect of Southern Ocean eddies on the ocean circulation is significant – they modulate the momentum balance of the zonal flow, and the meridional transport of tracers and mass. The strength of the eddy field is controlled by a combination of forcing (primarily thought to be wind stress) and intrinsic, chaotic, variability associated with the turbulent flow field itself. Here, we present results from an eddy-permitting ensemble of ocean model simulations to investigate the relative contribution of forced and intrinsic processes in governing the variability of Southern Ocean eddy kinetic energy. We find that variations of the eddy field are mostly random, even on longer (interannual) timescales. Where correlations between the wind stress forcing and the eddy field exist, these interactions are dominated by two distinct timescales – a fast baroclinic instability response; and a multi-year process owing to feedback between bathymetry and the mean flow. These results suggest that understanding Southern Ocean eddy dynamics and its larger-scale impacts requires an ensemble approach to eliminate intrinsic variability, and therefore may not yield robust conclusions from observations alone.
May 2022Published in Journal of Geophysical Research: Oceans volume 127 issue 5. 10.1029/2022JC018440