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| Titel |
Deep drivers of mesoscale circulation in the central Rockall Trough |
| VerfasserIn |
T. J. Sherwin, D. Aleynik, E. Dumont, M. E. Inall |
| 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 ; 11, no. 3 ; Nr. 11, no. 3 (2015-05-12), S.343-359 |
| Datensatznummer |
250117221
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| Publikation (Nr.) |
 copernicus.org/os-11-343-2015.pdf |
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| Zusammenfassung |
| Mesoscale variability in the central Rockall Trough, immediately west of the
British Isles, has been investigated using a combination of ship-borne,
underwater glider and gridded satellite altimeter measurements. Altimeter
observations show that eddies and large-scale circulation cells are
ubiquitous phenomena. They have horizontal length scales of order 100 km
with vertical scales of over 1000 m and are associated with mean current
speeds (over the upper 1000 m) of 15 ± 7 cm s−1. Monthly area
averaged surface eddy kinetic energy (EKE) has substantial inter-annual
variability, which at times can dominate a mean seasonal signal that varies
from a maximum in May (74 cm2 s−2) to a minimum in October
(52 cm2 s−2) and has increased gradually since 1992 at about
1.1 cm2 s−2 per year. This increase may be related to the retreat
of the sub-polar gyre (SPG). A 5 month glider mission in the trough showed
that the cyclonic component of EKE came from cold water features that are
located over 1000 m below the surface. The surface currents from altimeters
had similar magnitude to the drift currents averaged over 1000 m from the
glider in the stratified autumn, but were half the deep water speed during
late winter. Although the mesoscale features move in an apparent random
manner, they seem to be constrained by submarine topography such as
seamounts. Occasionally anti-cyclonic and cyclonic cells combine to cause a
coherent westward deflection of the European slope current that warms the
Rockall side of the trough. Such deflections contribute to the inter-annual
variability in the observed temperature and salinity that are monitored in
the upper 800 m of the trough. By combining glider and altimeter
measurements it is shown that altimeter measurements fail to observe a
15 cm s−1 northward flowing slope current on the eastern side as well
as a small persistent southward current on the western side. There is much to
be gained from the synergy between satellite altimetry and in situ glider
observations. |
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