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| Titel |
South Atlantic circulation in a world ocean model |
| VerfasserIn |
Matthew H. England, Véronique C. Garçon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 12, no. 9 ; Nr. 12, no. 9, S.812-825 |
| Datensatznummer |
250011081
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| Publikation (Nr.) |
 copernicus.org/angeo-12-812-1994.pdf |
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| Zusammenfassung |
| The circulation in the South Atlantic Ocean
has been simulated within a global ocean general circulation model. Preliminary
analysis of the modelled ocean circulation in the region indicates a rather
close agreement of the simulated upper ocean flows with conventional notions of
the large-scale geostrophic currents in the region. The modelled South Atlantic
Ocean witnesses the return flow and export of North Atlantic Deep Water (NADW)
at its northern boundary, the inflow of a rather barotropic Antarctic
Circumpolar Current (ACC) through the Drake Passage, and the inflow of warm
saline Agulhas water around the Cape of Good Hope. The Agulhas leakage amounts
to 8.7 Sv, within recent estimates of the mass transport shed westward at the
Agulhas retroflection. Topographic steering of the ACC dominates the structure
of flow in the circumpolar ocean. The Benguela Current is seen to be fed by a
mixture of saline Indian Ocean water (originating from the Agulhas Current) and
fresher Subantarctic surface water (originating in the ACC). The Benguela
Current is seen to modify its flow and fate with depth; near the surface it
flows north-westwards bifurcating most of its transport northward into the North
Atlantic Ocean (for ultimate replacement of North Atlantic surface waters lost
to the NADW conveyor). Deeper in the water column, more of the Benguela Current
is destined to return with the Brazil Current, though northward flows are still
generated where the Benguela Current extension encounters the coast of South
America. At intermediate levels, these northward currents trace the flow of
Antarctic Intermediate Water (AAIW) equatorward, though even more AAIW is seen
to recirculate poleward in the subtropical gyre. In spite of the model's rather
coarse resolution, some subtle features of the Brazil-Malvinas Confluence are
simulated rather well, including the latitude at which the two currents meet.
Conceptual diagrams of the recirculation and interocean exchange of thermocline,
intermediate and deep waters are constructed from an analysis of flows bound
between isothermal and isobaric surfaces. This analysis shows how the return
path of NADW is partitioned between a cold water route through the Drake Passage
(6.5 Sv), a warm water route involving the Agulhas Current sheeding thermocline
water westward (2.5 Sv), and a recirculation of intermediate water originating
in the Indian Ocean (1.6 Sv). |
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