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

journal contribution
posted on 2023-05-21, 08:49 authored by Ajitha Cyriac, Helen PhillipsHelen Phillips, Nathaniel BindoffNathaniel Bindoff, Polzin, K

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 Oceanography

Volume

52

Issue

8

Article number

1593–1611

Number

1593–1611

Pagination

1-19

ISSN

0022-3670

Department/School

Institute for Marine and Antarctic Studies

Publisher

Amer Meteorological Soc

Place of publication

45 Beacon St, Boston, USA, Ma, 02108-3693

Rights statement

© 2022 American Meteorological Society

Repository Status

  • Restricted

Socio-economic Objectives

Antarctic and Southern Ocean oceanic processes