Observed mean and mesoscale upper ocean circulation in the midlatitude northeast Atlantic - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research Année : 2005

Observed mean and mesoscale upper ocean circulation in the midlatitude northeast Atlantic

Résumé

Lagrangian instruments and altimetry data are used to investigate the upper (0 to $500 m) mean and mesoscale circulations in a region of the midlatitude northeast Atlantic (36°-47°N, 13°-23°W), a formation and subduction area of Subpolar Mode Water. Lagrangian data were collected between September 2000 and September 2001 with isobaric subsurface floats, totaling 34.0 float years, and surface drifting buoys, totaling 27.9 buoy years. The near-surface (0-100 m) mean circulation is dominated by two weak ($5 cm/s) eastward currents which veer southward in the domain. In the 100-to 500-m-deep layer, these eastward mean currents retroflect westward and form two anticyclonic circulation cells, opened to the west and separated by a cyclonic cell. Eddy kinetic energy is decreasing from the northwest to the southeast of the area, from $100-200 (cm/s) 2 to $20-30 (cm/s) 2. Long-lived anticyclones and cyclones display mean coherent displacements, both to the southwest. Westward eddy propagation speeds, close to that of long Rossby waves, increase southward and are consistent with a superposition of beta effect and advection by mean currents. Southward eddy displacements are coherent with the observed mean currents. In the north, anticyclones are seen to consist of Central and Subpolar Mode Water eddies, most of them likely originating from the eastern boundary, whereas in the south, most anticyclonic features result from the influence of ''Mediterranean Water Eddies'' (meddies) on the upper layers. Cyclonic activity is concentrated in ''cyclonic zones,'' which are seen to exchange floats and water properties.
Fichier principal
Vignette du fichier
2004JC002768.pdf (3.73 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-00124658 , version 1 (19-02-2021)

Identifiants

Citer

Bernard Le Cann, Michel Assenbaum, Jean-Claude Gascard, Gilles Reverdin. Observed mean and mesoscale upper ocean circulation in the midlatitude northeast Atlantic. Journal of Geophysical Research, 2005, 110, pp.C07S05. ⟨10.1029/2004JC002768⟩. ⟨hal-00124658⟩
177 Consultations
25 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More