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| Titel |
Transport and structure of the Weddell Gyre |
| VerfasserIn |
E. Fahrbach, G. Rohardt, M. Schröder, V. Strass |
| 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.840-855 |
| Datensatznummer |
250011083
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| Publikation (Nr.) |
 copernicus.org/angeo-12-840-1994.pdf |
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| Zusammenfassung |
| A cyclonic gyre controls the advection of
source waters into the formation areas of bottom water in the southern and
western parts of the Weddell Sea and the subsequent transport of modified water
masses to the north. Determination of the structure of the Weddell Gyre and of
the associated transports was one of the objectives of the "Weddell Gyre
Study" which began in September 1989 and ended in January 1993. The
collected data set comprises records of moored current meters and profiles of
temperature and salinity distributed along a transect between the northern tip
of the Antarctic Peninsula and Kapp Norvegia. The circulation pattern on the
transect is dominated by stable boundary currents of several hundred kilometers
width at the eastern and western sides of the basin. They are of comparable size
on both sides and provide nearly 90% of the volume transport of the gyre which
amounts to 29.5 Sv. In the interior, a weak anticyclonic cell of 800 km diameter
transports less than 4 Sv. Apart from the continental slopes, the near-bottom
currents flow at some locations in an opposite direction to those in the water
column above, indicating a significant baroclinic component of the current
field. The intensity of the boundary currents is subject to seasonal
fluctuations, whereas in the interior, time scales from days to weeks dominate.
The large-scale circulation pattern is persistent during the years 1989 to 1991.
The heat transport into the southern Weddell Sea is estimated to be 3.48×1013
W. This implies an equivalent heat loss through the sea surface of 19 W m-2,
as an average value for the area south of the transect. The derived salt
transport is not significantly different from zero; consequently, the salt gain
by sea ice formation has to compensate almost entirely the fresh water gain from
the melting ice shelves and from precipitation. Estimation of water mass
formation rates from the thermohaline differences of the inflow and outflow
through the transect indicates that 6.0 Sv of Warm Deep Water are transformed
into 2.6 Sv of Weddell Sea Bottom Water, into 1.2 Sv of Weddell Sea Deep Water,
and into 2.2 Sv of surface water. |
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