Influence of bottom topography on vortex stability
The effects of topography on the linear stability of both barotropic vortices and two-layer, baroclinic vortices are examined by considering cylindrical topography and vortices with stepwise relative vorticity profiles in the quasi-geostrophic approximation. Four vortex configurations are considered...
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| Format: | Article |
| Language: | English |
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American Meteorological Society
2020
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| Online Access: | https://hdl.handle.net/1721.1/124678 |
| _version_ | 1826197840308731904 |
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| author | Zhao, Bowen Chieusse-Gerard, Emma Flierl, Glenn |
| 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 Zhao, Bowen Chieusse-Gerard, Emma Flierl, Glenn |
| author_sort | Zhao, Bowen |
| collection | MIT |
| description | The effects of topography on the linear stability of both barotropic vortices and two-layer, baroclinic vortices are examined by considering cylindrical topography and vortices with stepwise relative vorticity profiles in the quasi-geostrophic approximation. Four vortex configurations are considered, classified by the number of relative vorticity steps in the horizontal and the number of layers in the vertical: barotropic one-step vortex (Rankine vortex), barotropic two-step vortex and their two-layer, baroclinic counterparts with the vorticity steps in the upper layer. In the barotropic calculation, the vortex is destabilized by topography having an oppositely signed potential vorticity jump while stabilized by topography of same-signed jump, i.e. anticyclones are destabilized by seamounts while stabilized by depressions. Further, topography of appropriate sign and magnitude can excite a mode-1 instability for a two-step vortex, especially relevant for topographic encounters of an otherwise stable vortex. The baroclinic calculation is in general consistent with the barotropic calculation except that the growth rate weakens and, for a two-step vortex, becomes less sensitive to topography (sign and magnitude) as baroclinicity increases. The smaller growth rate for a baroclinic vortex is consistent with previous findings that vortices with sufficient baroclinic structure could cross the topography relatively easily. Nonlinear contour dynamics simulations are conducted to confirm the linear stability analysis and to describe the subsequent evolution. Keywords: Baroclinic flows; Barotropic flows; Instability; Ocean dynamics; Topographic effects |
| first_indexed | 2024-09-23T10:54:37Z |
| format | Article |
| id | mit-1721.1/124678 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T10:54:37Z |
| publishDate | 2020 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/1246782022-09-27T15:53:00Z Influence of bottom topography on vortex stability Zhao, Bowen Chieusse-Gerard, Emma Flierl, Glenn Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences The effects of topography on the linear stability of both barotropic vortices and two-layer, baroclinic vortices are examined by considering cylindrical topography and vortices with stepwise relative vorticity profiles in the quasi-geostrophic approximation. Four vortex configurations are considered, classified by the number of relative vorticity steps in the horizontal and the number of layers in the vertical: barotropic one-step vortex (Rankine vortex), barotropic two-step vortex and their two-layer, baroclinic counterparts with the vorticity steps in the upper layer. In the barotropic calculation, the vortex is destabilized by topography having an oppositely signed potential vorticity jump while stabilized by topography of same-signed jump, i.e. anticyclones are destabilized by seamounts while stabilized by depressions. Further, topography of appropriate sign and magnitude can excite a mode-1 instability for a two-step vortex, especially relevant for topographic encounters of an otherwise stable vortex. The baroclinic calculation is in general consistent with the barotropic calculation except that the growth rate weakens and, for a two-step vortex, becomes less sensitive to topography (sign and magnitude) as baroclinicity increases. The smaller growth rate for a baroclinic vortex is consistent with previous findings that vortices with sufficient baroclinic structure could cross the topography relatively easily. Nonlinear contour dynamics simulations are conducted to confirm the linear stability analysis and to describe the subsequent evolution. Keywords: Baroclinic flows; Barotropic flows; Instability; Ocean dynamics; Topographic effects U.S.–Israel Science Foundation (Grant 2014206) 2020-04-15T20:14:17Z 2020-04-15T20:14:17Z 2019-12 2019-02 2020-04-09T12:18:30Z Article http://purl.org/eprint/type/JournalArticle 0022-3670 1520-0485 https://hdl.handle.net/1721.1/124678 Zhao, Bowen, et al. “Influence of Bottom Topography on Vortex Stability.” Journal of Physical Oceanography 49, 12 (December 2019): pp. 3199–219. © 2019 American Meteorological Society. en http://dx.doi.org/10.1175/JPO-D-19-0049.1 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 | Zhao, Bowen Chieusse-Gerard, Emma Flierl, Glenn Influence of bottom topography on vortex stability |
| title | Influence of bottom topography on vortex stability |
| title_full | Influence of bottom topography on vortex stability |
| title_fullStr | Influence of bottom topography on vortex stability |
| title_full_unstemmed | Influence of bottom topography on vortex stability |
| title_short | Influence of bottom topography on vortex stability |
| title_sort | influence of bottom topography on vortex stability |
| url | https://hdl.handle.net/1721.1/124678 |
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