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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American Meteorological Society
2018
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| Liŋkkat: | http://hdl.handle.net/1721.1/118188 https://orcid.org/0000-0002-3736-1956 |
| _version_ | 1826211435265392640 |
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| author | Nikurashin, Maxim Ferrari, Raffaele |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Nikurashin, Maxim Ferrari, Raffaele |
| author_sort | Nikurashin, Maxim |
| collection | MIT |
| 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 |
| first_indexed | 2024-09-23T15:05:50Z |
| format | Article |
| id | mit-1721.1/118188 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T15:05:50Z |
| publishDate | 2018 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/1181882022-09-29T12:41:32Z 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 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) 2018-09-28T13:52:33Z 2018-09-28T13:52:33Z 2010-05 2008-12 2018-09-21T17:20:30Z Article http://purl.org/eprint/type/JournalArticle 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 https://orcid.org/0000-0002-3736-1956 http://dx.doi.org/10.1175/2009JPO4199.1 Journal of Physical Oceanography 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. application/pdf American Meteorological Society American Meteorological Society |
| spellingShingle | Nikurashin, Maxim Ferrari, Raffaele Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory |
| title | 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_short | 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 |
| url | http://hdl.handle.net/1721.1/118188 https://orcid.org/0000-0002-3736-1956 |
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