Eddy activity and mixing in upwelling systems: a comparative study of Northwest Africa and California regions |
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Authors: | P Marchesiello P Estrade |
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Institution: | (1) Institut de Recherche pour le Développement, Noumea Center, BP A5, 98848 Noumea Cedex, New Caledonia;(2) Climate and Environmental Dynamics Laboratory, University of New South Wales, Sydney, NSW 2052, Australia |
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Abstract: | A comparative modeling approach is used to study the mesoscale dynamics of coastal transition zones in the upwelling systems
of Western Sahara and central California. It is shown that large differences in eddy activity and mixing exist between the
two systems. Since upwelling-favorable winds off Central California and Western Sahara have similar amplitudes, we suggest
that observed and modeled differences in eddy activity are due to differences in configuration parameters. It is argued that
two of these parameters, stratification and topography, eventually affect the energy available for the mesoscales through
baroclinic instability. The large difference in stratification appears to be linked to the salinity structure formed by the
large-scale circulation and is directly related to available potential energy. The shape of the continental shelf affects
the position, structure, and scale of the Ekman divergence, hence upwelling intensity, and frontal formation. The potential
impact of mesoscale eddy mixing and its variability on upwelling ecosystems is discussed. |
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Keywords: | |
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