Speaker:
Affiliation:
Date:
Venue:
Abstract:
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 redistri-
bution 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.