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Accueil > Actualités > Séminaires > Séminaires 2011

Mardi 17 mai 2011 à 11h, salle A103 du LEGI

Paul SPENCE, Climate Change Research Centre, University of New South Wales, Sydney, Australia.

Titre/Title :
Coarse versus ocean eddy-permitting global climate simulations.

Contact :
Julien Le Sommer

Résumé/Abstract :
Versions of a global climate model, with horizontal resolutions ranging from coarse to ocean eddy- permitting, are used to investigate the resolution dependence of the global ocean meridional overturning circulation. At coarse resolutions North Atlantic deepwater tends to upwell diabatically at low-latitudes, so that the Southern Ocean is weakly coupled with the rest of the ocean. As resolution increases and eddy effects become less parametrized the interior circulation becomes more adiabatic and deep water increasingly upwells by flowing along isopycnals in the Southern Ocean, despite each model having the same vertical diffusivity profile. At high resolutions much of the North Atlantic Deep Water (NADW) separates from the western boundary and enters the low-latitude Atlantic via interior pathways distinct from the Deep Western Boundary Current (DWBC). It is shown that bottom pressure torques play an important role in maintaining these interior NADW outflows.
Differences in the Southern Ocean response to poleward intensifying southern hemisphere winds through the 21st century, and the North Atlantic response to freshwater forcing are will be discussed.