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In the stratified ocean, turbulent mixing is primarily attributed to the breaking of internal waves. As such, internal waves provide a link between large-scale forcing and small-scale mixing. The internal wave field north of the Kerguelen Plateau is characterized using 914 high-resolution hydrographic profiles from novel Electromagnetic Autonomous Profiling Explorer (EM-APEX) floats. Altogether, 46 coherent features are identified in the EM-APEX velocity profiles and interpreted in terms of internal wave kinematics. The large number of internal waves analyzed provides a quantitative framework for characterizing spatial variations in the internal wave field and for resolving generation versus propagation dynamics. Internal waves observed near the Kerguelen Plateau have a mean vertical wavelength of 200 m, a mean horizontal wavelength of 15 km, a mean period of 16 h, and a mean horizontal group velocity of 3 cm s⁻¹. The internal wave characteristics are dependent on regional dynamics, suggesting that different generation mechanisms of internal waves dominate in different dynamical zones. The wave fields in the Subantarctic/Subtropical Front and the Polar Front Zone are influenced by the local small-scale topography and flow strength. The eddy-wave field is influenced by the large-scale flow structure, while the internal wave field in the Subantarctic Zone is controlled by atmospheric forcing. More importantly, the local generation of internal waves not only drives large-scale dissipation in the frontal region but also downstream from the plateau. Some internal waves in the frontal region are advected away from the plateau, contributing to mixing and stratification budgets elsewhere.

Item Type:	Refereed Article
Keywords:	Southern Ocean, mixing, internal waves, EM-APEX, observations, Antarctic Circumpolar Current, geographic location/entity, circulation/dynamics, wave properties, observational techniques, algorithms, in situ oceanic observations, profilers, oceanic
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Physical Oceanography
Objective Division:	Environment
Objective Group:	Climate and Climate Change
Objective Field:	Climate Variability (excl. Social Impacts)
UTAS Author:	Meyer, A (Dr Amelie Meyer)
UTAS Author:	Phillips, HE (Dr Helen Phillips)
ID Code:	104844
Year Published:	2016
Funding Support:	Australian Research Council (DP0877098)
Web of Science® Times Cited:	6
Deposited By:	Oceans and Cryosphere
Deposited On:	2015-11-22
Last Modified:	2018-02-02
Downloads:	0