Physical Oceanography Seminar – Dr. Andrew Thompson – Stirring up the Southern Ocean

Physical Oceanography Seminar – Dr. Andrew Thompson, California Institute of Technology

Title: “Stirring up the Southern Ocean: Submesoscale dynamics and ventilation in the ACC”

Abstract: Evidence continues to increase that submesoscale dynamics, motions characterized by O(1) Rossby number, make a leading order contribution to surface heat and other tracer fluxes. Both high resolution numerical models and intensive field experiments have identified a range of hydrodynamic instabilities that give rise to these submesoscale motions and govern their spatial and temporal variability. The Southern Ocean, and in particular the Antarctic Circumpolar Current (ACC), is characterized by properties typically conducive to submesoscale activity: a strong mesoscale eddy field and surface wind stress, persistent fronts, and weak vertical stratification. However, unique dynamics also occur in the Southern Ocean due to flow-topography interactions and the large seasonal cycle in sea ice formation and melt. In this presentation, I will summarize some of the key processes that shape submesoscale vertical velocities and fluxes in the Southern Ocean. I will also provide evidence that these dynamics lead to highly localized regions of ocean ventilation and water mass modification with implications for the Southern Ocean’s response to changing climate conditions.