Marchesiello Patrick, Estrade P. (2009). Eddy activity and mixing in upwelling systems : a comparative study of Northwest Africa and California regions. International Journal of Earth Sciences, 98 (2), p. 299-308. ISSN 1437-3254.
Titre du document
Eddy activity and mixing in upwelling systems : a comparative study of Northwest Africa and California regions
International Journal of Earth Sciences, 2009,
98 (2), p. 299-308 ISSN 1437-3254
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.
