Mardi 17 février - Eddy-driven meridional transport across the ACC upstream of Drake Passage
Feb 17, 2015
from 11:00 AM to 12:00 PM
Loic Jullion, Geophysical Fluid Dynamics Institute, Florida State University, Tallahassee, Florida, USA
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Geophysical Fluid Dynamics Institute, Florida State University, Tallahassee, Florida, USA
Titre: Eddy-driven meridional transport across the ACC upstream of Drake Passage
Résumé: The magnitude and vertical (density) distribution of the eddy-driven transport in the Southeastern Pacific sector of the Southern Ocean is inferred from observations and recent estimates of isopycnal diusivity from the Diapycnal and Isopycnal Mixing Experiments in the Southern Ocean (DIMES) experiment. A vertical profile of isopycnal diffusivity derived from numerical modelling and accoustically-tracked isopycnal floats released during DIMES is combined with historical CTD profiles. Away from the surface layer and above the depth of the sill of the Drake Passage, the eddy-driven flow is southward between γn = 27.5 and γn = 28.16 kg m^-3 before reversing to become northward where the Potential Vorticity gradient reverses. The calculated eddy velocities are small compared to other regions of the Southern Ocean where complex topography promotes instability and eddy transfer. These results lend support to the idea that local dynamics, dictated by flow-topography interactions, strongly influence the magnitude of the tracer transport in the Southern Ocean.