A high-resolution ocean model and satellite-based observations are used to understand the close interaction of waves and turbulence in the Antarctic Circumpolar Current (ACC). This analysis reveals the importance of radiation stresses in ACC dynamics which illustrate the organisation of turbulence by waves, giving rise to systematic, long-range momentum transports. It is then shown that in the ACC these long-range momentum transports, in the form of baroclinic jets and standing barotropic Rossby waves, are limited in range by major topographic features. Downstream of these topographic features standing Rossby waves become barotropically unstable, leading to regions of enhanced eddy kinetic energy and mixing of tracers, which are often referred to as oceanic storm tracks.
The dynamics of these radiation stresses is investigated by analysing both lateral eddy momentum fluxes, which are responsible for the conversion of energy between mean and eddy kinetic energy reservoirs, and the kinematic suppression of eddy diffusivities by the mean flow, which are closely related to the eddy momentum fluxes via the well-known Taylor identity. Additionally, the redistribution of eddy energy through the eddy energy flux is shown to be of importance in understanding the evolution of radiation stresses along the ACC. Finally, implications for the observation of hydrographic fronts and the parameterization of eddy fluxes are discussed.
University of Mississippi
Tue, 15/01/2019 - 12:00pm to 1:00pm
RC-M032, Red Centre, UNSW