Poster Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

How Meanders in the Southern Ocean Shape the MLD and impact Subduction in an Eddying Southern Ocean?  (#606)

Felipe Vilela-Silva 1 2 3 , Nathan Bindoff 1 2 4 , Helen Phillips 1 2 4 , Steve Rintoul 2 4 5 6 , Maxim Nikurashin 1 2 4
  1. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
  2. Australian Antarctic Program Partnership, University of Tasmania, Hobart, Tasmania, Australia
  3. ARC Centre of Excellence in Climate Extremes, University of Tasmania, Hobart, Tasmania, Australia
  4. Australian Centre for Excellence in Antarctic Science, University of Tasmania, Hobart, Tasmania, Australia
  5. Oceans and Atmosphere, CSIRO, Hobart, Tasmania, Australia
  6. Centre for Southern Hemisphere Oceans Research, CSHOR, Hobart, Tasmania, Australia

Standing meanders along the Antarctic Circumpolar Current (ACC) host regions of elevated eddy variability, meridional heat transport, and vertical exchange. In this study, we diagnose air-sea interaction and subsurface dynamics in a standing meander south of Australia and water subduction in an eddying Southern Ocean. We use the 1/10° ACCESS-OM2 ocean-sea ice model forced by the JRA55 atmospheric reanalysis. The thermodynamic and dynamical properties are compared to the position and flexing of the ACC’s Polar Front meander. The standing meander induces trough-to-crest variations in surface heat flux, mixed layer depth, wind stress curl, vertical velocity, and subduction. At the crests, the ocean loses heat, and the mixed layer is deeper. The opposite occurs at the troughs. Wind stress curl, vertical velocity and subduction change sign on entering and exiting crests and troughs. The difference in composites of a relaxed and flexed Polar Front meander highlights the link between vertical velocity and meander curvature. We also estimate the eddy-induced and Eulerian subduction in the Southern Ocean following the definition per se without any parameterization. These results are relevant for discussions about parameterization of the eddy-induced subduction of carbon and the Southern Ocean Overturning Circulation which play relevant roles in climate.