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| Titel |
Antarctic circumpolar transport and the southern mode: a model investigation of interannual to decadal timescales |
| VerfasserIn |
C. W. Hughes, Joanne Williams, A. C. Coward, B. A. de Cuevas |
| 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 ; 10, no. 2 ; Nr. 10, no. 2 (2014-04-10), S.215-225 |
| Datensatznummer |
250116966
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| Publikation (Nr.) |
 copernicus.org/os-10-215-2014.pdf |
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| Zusammenfassung |
| It is well-established that, at periods shorter than a year,
variations in Antarctic circumpolar transport are reflected in
a barotropic mode, known as the southern mode, in which sea level
and bottom pressure varies coherently around Antarctica. Here, we
use two multidecadal ocean model runs to investigate the behaviour
of the southern mode at timescales on which density changes become
important, leading to a baroclinic component to the adjustment. We
find that the concept of a southern mode in bottom pressure remains
valid, and remains a direct measure of the circumpolar transport,
with changes at the northern boundary playing only a small role even
on decadal timescales. However, at periods longer than about
5 years, density changes start to play a role, leading to
a surface intensification of the vertical profile of the
transport. We also find that barotropic currents on the continental
slope account for a significant fraction of the variability, and
produce surface intensification in the meridional-integral flow.
Circumpolar sea level and transport are related at all investigated
timescales. However, the role of density variations results in
a ratio of sea level change to transport which becomes larger at longer
timescales. This means that any long-term transport monitoring strategy
based on present measurement systems must involve multiplying the observed
quantity by a factor which depends on frequency. |
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