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Turbulent mixing variability in an energetic standing meander of the Southern Ocean

Citation

Cyriac, A and Phillips, HE and Bindoff, NL and Polzin, K, Turbulent mixing variability in an energetic standing meander of the Southern Ocean, Journal of Physical Oceanography, 52, (8) Article 1593-1611. ISSN 0022-3670 (2022) [Refereed Article]

Copyright Statement

2022 American Meteorological Society

DOI: doi:10.1175/JPO-D-21-0180.1

Abstract

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.

Item Details

Item Type:Refereed Article
Keywords:internal waves, mixing, ocean circulation, Southern Ocean, EM-APEX, floats, Antarctic Circumpolar Current, meander
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Cyriac, A (Ms Ajitha Cyriac)
UTAS Author:Phillips, HE (Associate Professor Helen Phillips)
UTAS Author:Bindoff, NL (Professor Nathan Bindoff)
ID Code:150661
Year Published:2022
Funding Support:Australian Research Council (DP170102162)
Deposited By:Oceans and Cryosphere
Deposited On:2022-06-24
Last Modified:2022-08-04
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