Journal article

Convection Enhances Mixing in the Southern Ocean

Taimoor Sohail, Bishakhdatta Gayen, Andrew McC Hogg

GEOPHYSICAL RESEARCH LETTERS | AMER GEOPHYSICAL UNION | Published : 2018

Abstract

Mixing efficiency is a measure of the energy lost to mixing compared to that lost to viscous dissipation. In a turbulent stratified fluid the mixing efficiency is often assumed constant at η = 0.2, whereas with convection it takes values closer to 1. The value of mixing efficiency when both stratified shear flow and buoyancy-driven convection are active remains uncertain. We use a series of numerical simulations to determine the mixing efficiency in an idealized Southern Ocean model. The model is energetically closed and fully resolves convection and turbulence such that mixing efficiency can be diagnosed. Mixing efficiency decreases with increasing wind stress but is enhanced by turbulent c..

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University of Melbourne Researchers

Grants

Awarded by Australian Research Council (ARC)


Awarded by Endeavour Scholarships and Fellowships


Awarded by ARC DECRA Fellowship


Funding Acknowledgements

Numerical simulations were conducted on the Australian National Computational Infrastructure (NCI), ANU, which is supported by the Commonwealth of Australia. This research was supported by the Australian Research Council (ARC) grant DP140103706. T. S. was supported by the Endeavour Scholarships and Fellowships 5256_2016, and B. G. by an ARC DECRA Fellowship DE140100089 and the R. J. L. Hawke Fellowship. We are grateful for the advice and direction provided by C. A. Vreugdenhil, R. W. Griffiths, and K. D. Stewart in earlier versions of this paper. We also thank two anonymous reviewers for their constructive feedback. Model outputs are available in the supporting information.