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Downstream propagation and remote dissipation of internal waves in the Southern Ocean

Citation

Zheng, K and Nikurashin, M, Downstream propagation and remote dissipation of internal waves in the Southern Ocean, Journal of Physical Oceanography, 49 pp. 1873-1887. ISSN 0022-3670 (2019) [Refereed Article]


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DOI: doi:10.1175/JPO-D-18-0134.1

Abstract

Recent microstructure observations in the Southern Ocean report enhanced internal gravity waves and turbulence in the frontal regions of the Antarctic Circumpolar Current extending a kilometer above rough bottom topography. Idealized numerical simulations and linear theory show that geostrophic flows impinging on rough small-scale topography are very effective generators of internal waves and estimate vigorous wave radiation, breaking, and turbulence within a kilometer above bottom. However, both idealized simulations and linear theory assume periodic and spatially uniform topography and tend to overestimate the observed levels of turbulent energy dissipation locally at the generation sites. In this study, we explore the downstream evolution and remote dissipation of internal waves generated by geostrophic flows using a series of numerical, realistic topography simulations and parameters typical of Drake Passage. The results show that significant levels of internal wave kinetic energy and energy dissipation are present downstream of the rough topography, internal wave generation site. About 30%–40% of the energy dissipation occurs locally over the rough topography region, where internal waves are generated. The rest of the energy dissipation takes place remotely and decays downstream of the generation site with an e-folding length scale of up to 20–30 km. The model we use is two-dimensional with enhanced viscosity coefficients, and hence it can result in the underestimation of the remote wave dissipation and its decay length scale. The implications of our results for turbulent energy dissipation observations and mixing parameterizations are discussed.

Item Details

Item Type:Refereed Article
Keywords:internal waves, mixing, remote dissipation, Southern Ocean, lee waves
Research Division:Engineering
Research Group:Fluid mechanics and thermal engineering
Research Field:Geophysical and environmental fluid flows
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Measurement and assessment of marine water quality and condition
UTAS Author:Nikurashin, M (Dr Maxim Nikurashin)
ID Code:137675
Year Published:2019
Funding Support:Australian Research Council (DE150100937)
Web of Science® Times Cited:11
Deposited By:Oceans and Cryosphere
Deposited On:2020-02-26
Last Modified:2020-03-20
Downloads:5 View Download Statistics

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