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Turbulent mixing variability in an energetic standing meander of the Southern Ocean
This study presents novel observational estimates of turbulent dissipation and mixing in a standing meander between the Southeast Indian Ridge and the Macquarie Ridge in the Southern Ocean. By applying a finescale parameterization on the temperature, salinity and velocity profiles collected from Electromagnetic Autonomous Profiling Explorer (EM-APEX) floats in the upper 1600 m, we estimated the intensity and spatial distribution of dissipation rate and diapycnal mixing along the float tracks and investigated the sources. The indirect estimates indicate strong spatial and temporal variability of turbulent mixing varying from O(10−6) − O(10−3) m2s−1 in the upper 1600 m. Elevated turbulent mixing is mostly associated with the Subantarctic Front (SAF) and mesoscale eddies. In the upper 500 m, enhanced mixing is associated with downward propagating wind-generated near-inertial waves as well as the interaction between cyclonic eddies and upward propagating internal waves. In the study region, the local topography does not play a role in turbulent mixing in the upper part of the water column, which has similar values in profiles over rough and smooth topography. However, both remotely-generated internal tides and lee waves could contribute to the upward propagating energy. Our results point strongly to the generation of turbulent mixing through the interaction of internal waves and the intense mesoscale eddy field.
Funding
Australian Research Council
History
Publication title
Journal of Physical OceanographyVolume
52Issue
8Article number
1593–1611Number
1593–1611Pagination
1-19ISSN
0022-3670Department/School
Institute for Marine and Antarctic StudiesPublisher
Amer Meteorological SocPlace of publication
45 Beacon St, Boston, USA, Ma, 02108-3693Rights statement
© 2022 American Meteorological SocietyRepository Status
- Restricted