Articles | Volume 10, issue 2
Ocean Sci., 10, 201–213, 2014
https://doi.org/10.5194/os-10-201-2014
Ocean Sci., 10, 201–213, 2014
https://doi.org/10.5194/os-10-201-2014

Research article 10 Apr 2014

Research article | 10 Apr 2014

Intrinsic variability of the Antarctic Circumpolar Current system: low- and high-frequency fluctuations of the Argentine Basin flow

G. Sgubin1, S. Pierini2, and H. A. Dijkstra3 G. Sgubin et al.
  • 1Institut Pierre Simon Laplace (IPSL), Paris, France
  • 2Dipartimento di Scienze e Tecnologie, Università di Napoli Parthenope, Centro Direzionale, Isola C4, 80143 Naples, Italy
  • 3Institute for Marine and Atmospheric research Utrecht, Utrecht University, Utrecht, the Netherlands

Abstract. In this paper, the variability of the Antarctic Circumpolar Current system produced by purely intrinsic nonlinear oceanic mechanisms is studied through a sigma-coordinate ocean model, implemented in a large portion of the Southern Ocean at an eddy-permitting resolution under steady surface heat and momentum fluxes. The mean transport through the Drake Passage and the structure of the main Antarctic Circumpolar Current fronts are well reproduced by the model. Intrinsic variability is found to be particularly intense in the Subantarctic Front and in the Argentine Basin, on which further analysis is focused. The low-frequency variability at interannual timescales is related to bimodal behavior of the Zapiola Anticyclone, with transitions between a strong and collapsed anticyclonic circulation in substantial agreement with altimeter observations. Variability on smaller timescales shows clear evidence of topographic Rossby-wave propagation along the eastern and southern flanks of the Zapiola Rise and of mesoscale eddies, also in agreement with altimeter observations. The analysis of the relationship between the low- and high-frequency variability suggests possible mechanisms of mutual interaction.

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