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| Titel |
Influence of the Southern Annular Mode on the sea ice-ocean system: the role of the thermal and mechanical forcing |
| VerfasserIn |
W. Lefebvre, H. Goosse |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 1, no. 3 ; Nr. 1, no. 3 (2005-11-14), S.145-157 |
| Datensatznummer |
250000214
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| Publikation (Nr.) |
 copernicus.org/os-1-145-2005.pdf |
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| Zusammenfassung |
| The global sea ice-ocean model ORCA2-LIM is used to investigate the impact
of the thermal and mechanical forcing associated with the Southern Annular Mode
(SAM) on the Antarctic sea ice-ocean system. The model is
driven by idealized forcings based on regressions between the wind stress and the
air temperature at one hand and the SAM index the other hand. The wind-stress component strongly affects the
overall patterns of the ocean circulation with a northward surface drift, a
downwelling at about 45° S and an upwelling in the vicinity of the
Antarctic continent when the SAM is positive. On the other hand, the thermal
forcing has a negligible effect on the ocean currents. For sea ice, both the
wind-stress (mechanical) and the air temperature (thermal) components have a
significant impact. The mechanical part induces a decrease of the sea ice
thickness close to the continent and a sharp decrease of the mean sea ice
thickness in the Weddell sector. In general, the sea ice area also
diminishes, with a maximum decrease in the Weddell Sea. On the contrary, the
thermal part tends to increase the ice concentration in all sectors except in
the Weddell Sea, where the ice area shrinks. This thermal effect is the
strongest in autumn and in winter due to the larger temperature differences
associated with the SAM during these seasons. The sum of the thermal and
mechaninal effects gives a dipole response of sea ice to the SAM, with a
decrease of the ice area in the Weddell Sea and around the Antarctic
Peninsula and an increase in the Ross and Amundsen Seas during high SAM
years. This is in good agreement with the observed response of the ice cover
to the SAM. |
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