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| Titel |
Deep ocean exchange with west-European shelf seas |
| VerfasserIn |
J. M. Huthnance, J. T. Holt, S. L. Wakelin |
| 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 ; 5, no. 4 ; Nr. 5, no. 4 (2009-12-07), S.621-634 |
| Datensatznummer |
250002736
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| Publikation (Nr.) |
 copernicus.org/os-5-621-2009.pdf |
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| Zusammenfassung |
| We review mechanisms and studies of exchange between the north-east Atlantic
and the adjacent shelf seas. Well-developed summer upwelling and associated
filaments off Portugal and north-west Spain give exchange O(3 m2/s per
unit length of shelf). Prevailing westerly winds further north drive
exchange O(1 m2/s). Poleward flow along most of the upper slope has
associated secondary circulation O(1 m2/s), meanders and eddies. Eddies
are shed from slope waters into the Bay of Biscay, and local exchanges occur
at shelf spurs and depressions or canyons (e.g. dense-water cascading of
order 1 m2/s). Tidal transports are larger, but their reversal every
six hours makes exchange largely ineffective except where internal tides are
large and non-linear, as in the Celtic Sea where solitons carry water with
exchange O(1 m2/s). These various physical exchanges amount to an
estimated 2–3 m2/s per unit length of shelf, between ocean and shelf. A
numerical model estimate is comparable: 2.5×106 m3/s onto and
off the shelf from Brittany to Norway. Mixing controls the seasonal
thermocline, affecting primary production and hence fluxes and fate of
organic matter. Specifically, CO2 take-up by primary production,
settling below the thermocline before respiration, and then off-shelf
transport, make an effective shelf-sea "pump" (for CO2 from the
atmosphere to the deep ocean). However, knowledge of biogeochemical fluxes
is generally sparse, giving scope for more measurements, model validation
and estimates from models. |
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