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Coupled ocean/sea ice dynamics of the Antarctic Slope Current driven by topographic eddy suppression and sea ice momentum redistribution
  • Yidongfang Si,
  • Andrew Stewart,
  • Ian Eisenman
Yidongfang Si
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles

Corresponding Author:[email protected]

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Andrew Stewart
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles
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Ian Eisenman
Scripps Institution of Oceanography, University of California, San Diego
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The Antarctic Slope Current (ASC) plays a central role in redistributing water masses, sea ice, and tracer properties around the Antarctic margins, and in mediating cross-slope exchanges. While the ASC has historically been understood as a wind-driven circulation, recent studies have highlighted important momentum transfers due to mesoscale eddies and tidal flows. Furthermore, momentum input due to wind stress is transferred through sea ice to the ASC during most of the year, yet previous studies have typically considered the circulations of the ocean and sea ice independently. Thus it remains unclear to what extent the momentum input from the winds is mediated by sea ice, tidal forcing, and transient eddies in the ocean, and how the resulting momentum transfers serve to structure the ASC. In this study the dynamics of the coupled ocean/sea ice ASC circulation are investigated using high-resolution process-oriented simulations, and interpreted with the aid of a reduced-order model. In almost all simulations considered here, sea ice redistributes almost 100% of the wind stress away from the continental slope, resulting in approximately identical sea ice and ocean surface flows in the core of the ASC. This ice-ocean coupling results from suppression of vertical momentum transfer by mesoscale eddies over the continental slope, which allows the sea ice to accelerate the ocean surface flow until the speeds coincide. Tidal acceleration of the along-slope flow exaggerates this effect, and may even result in ocean-to-ice momentum transfer. The implications of these findings for along-and across-slope transport of water masses and sea ice around Antarctica are discussed.
Jul 2022Published in Journal of Physical Oceanography volume 52 issue 7 on pages 1563-1589. https://doi.org/10.1175/JPO-D-21-0142.1