Lagrangian circulation of the North Atlantic Central Water over the abyssal plain and continental slopes of the Bay of Biscay: description of selected mesoscale features

Type Article
Date 2006-06
Language English
Author(s) Serpette A1, Le Cann Bernard2, 3, Colas Francois3
Affiliation(s) 1 : CMO, EPSHOM, Serv Hydrog & Oceanog Marine, F-29603 Brest, France.
2 : Univ Bretagne Occidentale, Lab Phys Oceans, Unite Mixte CNRS, IFREMER,LPO UMR 6523, F-29238 Brest 3, France.
Source Scientia Marina (0214-8358) (Institut de Ciències del Mar de Barcelona, CSIC), 2006-06 , Vol. 70 , N. S1 , P. 27-42
WOS© Times Cited 19
Keyword(s) slope ocean exchanges, mesoscale eddies, slope current, Lagrangian floats and surface drifters, Bay of Biscay
Abstract Between 1994 and 2001, several experiments (ARCANE, SEFOS, INTERAFOS) were conducted to directly measure the general and mesoscale Lagrangian circulations over the Bay of Biscay abyssal plain and slopes. Two levels (~100 m and ~450 m) were selected to cover the North Atlantic Central Water range. Two types of Lagrangian instruments, drogued surface drifters tracked by satellite (Surdrift) and acoustically tracked subsurface floats (Rafos and Marvor), were used. Overall, more than 36 instrument-years were collected in the Bay of Biscay region (43-49°N, 01-12°W). The weak general circulation in the Bay of Biscay is seen to be highly influenced by the occurrence of several mesoscale coherent features, notably slope currents and eddies, and these affect the exchanges between the abyssalplain and the slopes. The objective of this paper is to depict some specific examples of the observed mesoscale field. Selected float trajectories are shown and used to discuss observations of slope currents and of both anticyclonic and cyclonic eddies. Slope currents exhibit alternation of poleward and equatorward directions, depending on both the period and the geographic area considered. Although the generation process of mesoscale eddies is difficult to observe unambiguously from Lagrangian instruments, eddies are nevertheless ubiquitous over the abyssal plain. Some characteristics of the observed cyclonic and anticyclonic eddies are presented. Smaller anticyclones, localised over the outer shelf and interpreted in terms of ajustment of slope water intrusions, are also depicted.
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Serpette A, Le Cann Bernard, Colas Francois (2006). Lagrangian circulation of the North Atlantic Central Water over the abyssal plain and continental slopes of the Bay of Biscay: description of selected mesoscale features. Scientia Marina, 70(S1), 27-42. Open Access version : https://archimer.ifremer.fr/doc/00000/6435/