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The impact of finite-amplitude bottom topography on internal wave generation in the Southern Ocean

Citation

Nikurashin, M and Ferrari, R and Grisouard, N and Polzin, N, The impact of finite-amplitude bottom topography on internal wave generation in the Southern Ocean, Journal of Physical Oceanography, 44, (11) pp. 2938-2950. ISSN 0022-3670 (2014) [Refereed Article]

Copyright Statement

Copyright 2014 American Meteorological Society

DOI: doi:10.1175/JPO-D-13-0201.1

Abstract

Direct observations in the Southern Ocean report enhanced internal wave activity and turbulence in a kilometer-thick layer above rough bottom topography collocated with the deep-reaching fronts of the Antarctic Circumpolar Current. Linear theory, corrected for finite-amplitude topography based on idealized, two dimensional numerical simulations, has been recently used to estimate the global distribution of internal wave generation by oceanic currents and eddies. The global estimate shows that the topographic wave generation is a significant sink of energy for geostrophic flows and a source of energy for turbulent mixing in the deep ocean. However, comparison with recent observations from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean shows that the linear theory predictions and idealized two-dimensional simulations grossly overestimate the observed levels of turbulent energy dissipation. This study presents two- and three-dimensional, realistic topography simulations of internal lee-wave generation from a steady flow interacting with topography with parameters typical of Drake Passage. The results demonstrate that internal wave generation at three dimensional, finite bottom topography is reduced compared to the two-dimensional case. The reduction is primarily associated with finite-amplitude bottom topography effects that suppress vertical motions and thus reduce the amplitude of the internal waves radiated from topography. The implication of these results for the global lee wave generation is discussed.

Item Details

Item Type:Refereed Article
Keywords:ocean mixing, internal waves, mixing parameterization, lee waves, topography
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Change Models
Author:Nikurashin, M (Dr Maxim Nikurashin)
ID Code:96512
Year Published:2014
Web of Science® Times Cited:8
Deposited By:IMAS Research and Education Centre
Deposited On:2014-11-10
Last Modified:2017-11-01
Downloads:0

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