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Accueil > Équipes > Equipe MEIGE : Modélisation, Expériences et Instrumentation pour la Géophysique et l’Environnement > Diffusion scientifique > Séminaires internes

Oceanic Circulation and Dynamical Processes Around the Reykjanes Ridge. Numerical Simulations and Laboratory Experiments

Thibault Jougla, 25/06/2014

The Reykjanes ridge is situated between the Irminger basin and the Iceland basin, at the intersection of different flows determining the global ocean circulation. The flow coming from the Faroe Bank channel turns around the ridge. The aim of this project is to understand the dynamic processes around the ridge. To the best of our knowledge idealized studies on the circulation around sloping ridges, focusing on meso- and sub-meso-scale structures are scant.

For this study, idealized numerical simulations and qualitative laboratory experiments have been performed. I used a fine resolution reduced gravity rotating shallow-water model to investigate the oceanic flow around a ridge, which I developed from scratch. After, validation of the ridge configuration for a variety of experiments over extended periods, and laminar to turbulent flows, I analyze the flow behavior around the ridge for the different regimes. In parallel, we have done some laboratory experiments using a novel measuring technique based on optical methods, showing the adequation of this method for studying ridge flows.

For laminar and turbulent flows, while turning around the ridge, coastal waves propagate from the injection to the upwelling areas. For high injection rates the flow is turbulent and shows asymmetry between the two sides of the ridge. For turbulent flows, eddies are released from the ridge front, forming beta-plumes. Around the ridge, smaller eddies and filaments emerge from larger scale eddies. To investigate the dynamics, a scale analysis, Hovmoller diagrams, and age tracers are used.

The eddies flow arriving to the ridge is transformed to a succession of beta-plumes. The speed of eddies increases approaching the north-eastern boundary.