Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory
Observations and inverse models suggest that small-scale turbulent mixing is enhanced in the Southern Ocean in regions above rough topography. The enhancement extends O(1) km above the topography, suggesting that mixing is supported by the breaking of gravity waves radiated from the ocean bottom. In...
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ftmit:oai:dspace.mit.edu:1721.1/118188 2023-06-11T04:11:19+02:00 Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory Nikurashin, Maxim Ferrari, Raffaele Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Ferrari, Raffaele 2018-09-21T17:20:30Z application/pdf http://hdl.handle.net/1721.1/118188 unknown American Meteorological Society http://dx.doi.org/10.1175/2009JPO4199.1 Journal of Physical Oceanography 0022-3670 1520-0485 http://hdl.handle.net/1721.1/118188 Nikurashin, Maxim, and Raffaele Ferrari. “Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory.” Journal of Physical Oceanography 40, 5 (May 2010): 1055–1074 © 2010 American Meteorological Society orcid:0000-0002-3736-1956 Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Meteorological Society Article http://purl.org/eprint/type/JournalArticle 2018 ftmit https://doi.org/10.1175/2009JPO4199.1 2023-05-29T08:44:52Z Observations and inverse models suggest that small-scale turbulent mixing is enhanced in the Southern Ocean in regions above rough topography. The enhancement extends O(1) km above the topography, suggesting that mixing is supported by the breaking of gravity waves radiated from the ocean bottom. In this study, it is shown that the observed mixing rates can be sustained by internal waves generated by geostrophic motions flowing over bottom topography. Weakly nonlinear theory is used to describe the internal wave generation and the feedback of the waves on the zonally averaged flow. Vigorous inertial oscillations are driven at the ocean bottom by waves generated at steep topography. The wave radiation and dissipation at equilibrium is therefore the result of both geostrophic flow and inertial oscillations differing substantially from the classical lee-wave problem. The theoretical predictions are tested versus two-dimensional highresolution numerical simulations with parameters representative of Drake Passage. This work suggests that mixing in Drake Passage can be supported by geostrophic motions impinging on rough topography rather than by barotropic tidal motions, as is commonly assumed. Keywords: Topographic effects; Internal waves; Southern Ocean; Gravity waves; Small scale processes National Science Foundation (U.S.) (Award OCE-6919248) Article in Journal/Newspaper Drake Passage Southern Ocean DSpace@MIT (Massachusetts Institute of Technology) Southern Ocean Drake Passage Journal of Physical Oceanography 40 5 1055 1074 |
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DSpace@MIT (Massachusetts Institute of Technology) |
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description |
Observations and inverse models suggest that small-scale turbulent mixing is enhanced in the Southern Ocean in regions above rough topography. The enhancement extends O(1) km above the topography, suggesting that mixing is supported by the breaking of gravity waves radiated from the ocean bottom. In this study, it is shown that the observed mixing rates can be sustained by internal waves generated by geostrophic motions flowing over bottom topography. Weakly nonlinear theory is used to describe the internal wave generation and the feedback of the waves on the zonally averaged flow. Vigorous inertial oscillations are driven at the ocean bottom by waves generated at steep topography. The wave radiation and dissipation at equilibrium is therefore the result of both geostrophic flow and inertial oscillations differing substantially from the classical lee-wave problem. The theoretical predictions are tested versus two-dimensional highresolution numerical simulations with parameters representative of Drake Passage. This work suggests that mixing in Drake Passage can be supported by geostrophic motions impinging on rough topography rather than by barotropic tidal motions, as is commonly assumed. Keywords: Topographic effects; Internal waves; Southern Ocean; Gravity waves; Small scale processes National Science Foundation (U.S.) (Award OCE-6919248) |
author2 |
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Ferrari, Raffaele |
format |
Article in Journal/Newspaper |
author |
Nikurashin, Maxim Ferrari, Raffaele |
spellingShingle |
Nikurashin, Maxim Ferrari, Raffaele Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory |
author_facet |
Nikurashin, Maxim Ferrari, Raffaele |
author_sort |
Nikurashin, Maxim |
title |
Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory |
title_short |
Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory |
title_full |
Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory |
title_fullStr |
Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory |
title_full_unstemmed |
Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory |
title_sort |
radiation and dissipation of internal waves generated by geostrophic motions impinging on small-scale topography: theory |
publisher |
American Meteorological Society |
publishDate |
2018 |
url |
http://hdl.handle.net/1721.1/118188 |
geographic |
Southern Ocean Drake Passage |
geographic_facet |
Southern Ocean Drake Passage |
genre |
Drake Passage Southern Ocean |
genre_facet |
Drake Passage Southern Ocean |
op_source |
American Meteorological Society |
op_relation |
http://dx.doi.org/10.1175/2009JPO4199.1 Journal of Physical Oceanography 0022-3670 1520-0485 http://hdl.handle.net/1721.1/118188 Nikurashin, Maxim, and Raffaele Ferrari. “Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory.” Journal of Physical Oceanography 40, 5 (May 2010): 1055–1074 © 2010 American Meteorological Society orcid:0000-0002-3736-1956 |
op_rights |
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. |
op_doi |
https://doi.org/10.1175/2009JPO4199.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
40 |
container_issue |
5 |
container_start_page |
1055 |
op_container_end_page |
1074 |
_version_ |
1768386277699223552 |