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Accueil > Actualités > Séminaires > Séminaires 2011

Mardi 12 avril 2011 à 11h00 - salle A103 LEGI

Bruno DEREMBLE, Florida State University

Titre/Title :
Multiple Equilibria and Oscillatory Modes in a Mid-Latitude Ocean-Atmosphere Model.

Contact :
Thierry Penduff

Résumé/Abstract :
Atmospheric response to a mid-latitude sea surface temperature (SST) front is studied, while emphasizing low-frequency modes induced by the presence of such a front. An idealized atmospheric quasi-geostrophic (QG) model is forced by the SST field of an idealized oceanic QG model. First, we recall equilibria of the oceanic model and the associated SST fronts. Next, these equilibria are used to force the atmospheric model and compute its equilibria when varying the strength of the oceanic forcing.

Low-frequency modes of atmospheric variability are identified and associated with successive Hopf bifurcations. The origin of these Hopf bifurcations is studied in detail. Finally, a link is established between the model’s time integrations and the previously obtained equilibria and oscillatory modes.