| 12 Oct 2026
Circulation, tides, and mixing at a seamount off the Antarctic Peninsula
Abstract. Seamounts are hotspots of ocean mixing and current–topography interactions. This study investigates the circulation, tidal influence, and potential for instabilities and mixing over a seamount on the South Scotia Ridge near the tip of the Antarctic Peninsula. The seamount is 20–50 km across and rises from 1200 m to within 300 m of the surface. It is known to host a stationary anticyclonic eddy associated with the bifurcation of the Antarctic Slope Front, yet the underlying dynamics remain unclear. We analyse in situ hydrographic and velocity data from two Seaglider surveys, complemented by a barotropic tide model and satellite measurements. Horizontal velocities derived from glider drift reveal a complex interplay between topography and energetic tides of up to 0.8 m s⁻¹. De-tided residuals reveal an anticyclonic circulation of 0.1–0.3 m s⁻¹ around the seamount, with a transport of about 1.5 Sv. The observations support the presence of a stratified Taylor column and topographic steering. Diagnostics suggest that tidal rectification accounts for up to 66 % of the residual current. An upscale energy transfer from small-scale turbulence over the slope may supply the additional energy required to maintain the eddy. Strong tides over the steep topography favour internal tide generation and hydraulic control, while weak stratification and strong horizontal shear leave the flow susceptible to submesoscale instability. Stratification is reduced over the summit, where vigorous turbulent mixing counteracts frictional downwelling and supports net upwelling, creating a diapycnal chimney over the seamount. Overall, the seamount emerges as a dynamic site for localised energy dissipation and upwelling, with implications for sea ice retreat, iceberg drift, and nutrient supply to the euphotic zone. Similar conditions are expected at other tidally energetic seamounts in high latitudes, where the dominant diurnal tidal constituents are subinertial.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Ocean Science.
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