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A Mechanism for Local Dissipation of Internal Tides Generated at Rough Topography

journal contribution
posted on 2023-05-17, 13:22 authored by Maxim NikurashinMaxim Nikurashin, Legg, S
Fine- and micro-structure observations indicate that turbulent mixing is enhanced within O(1) km above rough topography. Enhanced mixing is associated with internal wave breaking and, in many regions of the ocean, has been linked to the breaking and dissipation of internal tides. The generation and dissipation of internal tides are explored in this study using a high-resolution two-dimensional nonhydrostatic numerical model, which explicitly resolves the instabilities leading to wave breaking, configured in an idealized domain with a realistic multiscale topography and flow characteristics. The control simulation, chosen to represent the Brazil Basin region, produces a vertical profile of energy dissipation and temporal characteristics of finescale motions that are consistent with observations. Results suggest that a significant fraction of mixing in the bottom O(1) km of the ocean is sustained by the transfer of energy from the large-scale internal tides to smaller-scale internal waves by nonlinear wave–wave interactions. The time scale of the energy transfer to the smaller scales is estimated to be on the order of a few days. A suite of sensitivity experiments is carried out to examine the dependence of the energy transfer time scale and energy dissipation on topographic roughness, tidal amplitude, and Coriolis frequency parameters. Implications for tidal mixing parameterizations are discussed.

History

Publication title

Journal of Physical Oceanography

Volume

41

Issue

February

Pagination

378-395

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

© Copyright 2011 AMS

Repository Status

  • Restricted

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