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| Titel |
Southern Ocean overturning across streamlines in an eddying simulation of the Antarctic Circumpolar Current |
| VerfasserIn |
A. M. Treguier, M. H. England, S. R. Rintoul, G. Madec, J. Sommer, J.-M. Molines |
| 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 ; 3, no. 4 ; Nr. 3, no. 4 (2007-12-19), S.491-507 |
| Datensatznummer |
250001199
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| Publikation (Nr.) |
 copernicus.org/os-3-491-2007.pdf |
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| Zusammenfassung |
| An eddying global model is used to study the characteristics of the Antarctic
Circumpolar Current (ACC) in a streamline-following framework. Previous
model-based estimates of the meridional circulation were calculated using
zonal averages: this method leads to a counter-intuitive poleward circulation
of the less dense waters, and underestimates the eddy effects. We show that
on the contrary, the upper ocean circulation across streamlines agrees with
the theoretical view: an equatorward mean flow partially cancelled by a
poleward eddy mass flux. Two model simulations, in which the buoyancy forcing
above the ACC changes from positive to negative, suggest that the
relationship between the residual meridional circulation and the surface
buoyancy flux is not as straightforward as assumed by the simplest
theoretical models: the sign of the residual circulation cannot be inferred
from the surface buoyancy forcing only. Among the other processes that likely
play a part in setting the meridional circulation, our model results
emphasize the complex three-dimensional structure of the ACC (probably not
well accounted for in streamline-averaged, two-dimensional models) and the
distinct role of temperature and salinity in the definition of the density
field. Heat and salt transports by the time-mean flow are important even
across time-mean streamlines. Heat and salt are balanced in the ACC, the
model drift being small, but the nonlinearity of the equation of state cannot
be ignored in the density balance. |
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