Surface circulation in the Iroise Sea (W. Brittany) from high resolution HF radar mapping

Sentchev, Alexei; Forget, Philippe; Barbin, Yves; Yaremtchuk, M.

Type de document :

Article dans une revue scientifique: Article original

DOI :

10.1016/j.jmarsys.2011.11.024

Titre :

Surface circulation in the Iroise Sea (W. Brittany) from high resolution HF radar mapping

Auteur(s) :

Sentchev, Alexei [Auteur correspondant]

Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Forget, Philippe [Auteur]
Laboratoire de sondages électromagnétiques de l'environnement terrestre [LSEET]
Barbin, Yves [Auteur]
Laboratoire de sondages électromagnétiques de l'environnement terrestre [LSEET]
Yaremtchuk, M. [Auteur]
Naval Research Laboratory [NRL]

Titre de la revue :

Journal of Marine Systems

Pagination :

S153-S168

Éditeur :

Elsevier

Date de publication :

2013

ISSN :

0924-7963

Mot(s)-clé(s) :

Radar HF
courant de surface
méthode Haute résolution
mer à marée

Mot(s)-clé(s) en anglais :

HF radar
Tidal current
Residual flow
Eddy field
Iroise Sea

Discipline(s) HAL :

Planète et Univers [physics]/Sciences de la Terre/Océanographie

Résumé :

Etude à haute résolution par radar HF de la circulation en mer d'Iroise (Ouest Bretagne)

Résumé en anglais : [en]

The data from two high-frequency radars (HFR) operating in the Iroise Sea are re-processed by applying animproved version of the direction finding algorithm, removing wave-induced surface currents and the variational ...
Lire la suite >The data from two high-frequency radars (HFR) operating in the Iroise Sea are re-processed by applying animproved version of the direction finding algorithm, removing wave-induced surface currents and the variational interpolation on a regular grid. Combining these processing techniques allowed reconstruction ofthe surface currents at a level of details that was not previously available. Refined resolution enabled to identify fine-scale structures of surface circulation, to quantify the variability of tidal currents and the residual(time averaged) velocity field, and to explain spatial intermittence in polarization of the tidal current ellipses.The analyzed data span two month-long periods in spring and late summer of 2007. The major findings include (a) a dipole structure in the vorticity field characterized by two oppositely rotating eddies, generatedon the leeward side of the Ushant Island at flood (negative polarity) and at ebb (positive polarity); (b) an extremely strong fortnightly variability of tidal currents northwest of the Ushant Island with the highest velocity magnitude of 3.9 m/s caused by the interference of the major semi-diurnal tidal constituents; (c) asignificant contribution of the higher order nonlinear tidal harmonics to the surface currents in the Fromveurstrait, which maintains strong tidal currents and affects the shape of their fortnightly modulation. The residual circulation is characterized by two distinct zones approximately separated by the 100 m isobath: in theoffshore zone the residual currents have a significant contribution of the wind-driven component, whereasthe nearshore zone is characterized by extremely strong (up to 0.4 m/s) time-independent residual circulation featuring two permanent anticyclonic eddies: north of the western extremity of the Sein archipelago,and north the Ushant Island. The acquired data and the presented results could be useful for regionalmodel validation and studies of the local eddy dynamics, tidal fronts, and passive tracer transport in theregionLire moins >

Langue :

Anglais

Comité de lecture :

Oui

Audience :

Internationale

Vulgarisation :

Non

Collections :

Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL

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