Dynamics of the wind-driven sea level variation around Antarctica
Coastal sea level variation around Antarctica is characterized by a coherent (circumpolarly in-phase)fluctuation, correlated with the Antarctic Oscillation (AAO). This study addresses the dynamics of the wind-drivensea level variation around Antarctica. A realistic barotropic numerical model reprodu...
| Published in: | Journal of Physical Oceanography |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Amer Meteorological Soc
2009
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| Subjects: | |
| Online Access: | https://doi.org/10.1175/2008JPO3982.1 http://ecite.utas.edu.au/109891 |
| Summary: | Coastal sea level variation around Antarctica is characterized by a coherent (circumpolarly in-phase)fluctuation, correlated with the Antarctic Oscillation (AAO). This study addresses the dynamics of the wind-drivensea level variation around Antarctica. A realistic barotropic numerical model reproduced well theobserved sea level around Antarctica. From numerical model experiments, the authors demonstrate that theforcing responsible for the coastal sea level is the wind stress at the coastal boundary. Both the dominantcoherent signal and westward propagating signals are identified in the model, and these signals are trappedover the shelf and slope around Antarctica. As a mechanism of these trapped signals, the authors consideranalytical solutions of the oceanic response to alongshore wind stress over the shelf and slope in the circumpolardomain. In these solutions, besides the shelf wave mode, a wavenumber-zero mode appears andcharacterizes the coastal dynamics around Antarctica. At periods from 10 to 200 days, the coherent sea levelcan be explained quantitatively by the solution of this wavenumber-zero mode with a 510-day damping timescale. The spectral peaks of the westward propagating signals can be explained by the resonance of the shelfwave mode. The wavenumber-zero mode can respond to the wavenumber-zero forcing at any frequency andthe degree of response increases with decreasing frequency. In addition, the wavenumber-zero component ofwind stress, corresponding to the AAO variation, is a dominant forcing. Therefore, the coherent sea levelvariation around Antarctica is preferably generated and becomes a dominant feature in the circumpolardomain, particularly at lower frequencies. |
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