Eddy-driven dispersion processes in the Canary Current upwelling system: comparison with the California system

Upwelling ecosystems are characterized by high primary production due to sustained nutrient input by the vertical circulation. Upwelling zones also provide a very dispersive environment where nutrients, phytoplankton, zooplankton and meroplankton can be quickly swept from the coastal area. Usually, sardines and anchovies, essential components of the ecosystem and the local fisheries, tend to avoid the upwelling zones for spawning (Roy et al., 1992), although examples of the opposite can be found off southern Morocco and Senegal. Spawning success may be related to the physical environment through a balance between various processes of enrichment, retention/dispersion and concentration (Bakun, 1998). It is one of the objectives of this study to understand the mechanisms that govern spawning of small pelagic fish and the variability in time and space of these mechanisms. Modeling Approach The Regional Oceanic Modeling System (ROMS; Shchepetkin and McWilliams, 2003) was developed to simulate both coastal and oceanic regions and their interactions. ROMS solves the primitive equations in an Earth-centered rotating environment, based on the Boussinesq approximation and hydrostatic vertical momentum balance. The model grid, forcing, initial and boundary conditions are built using the ROMSTOOLS package (Penven, 2003). Our strategy for managing the large range of scales from regional down to the local scales is a multi-level approach based on the AGRIF package developed by Blayo and Debreu (1999). This is an online (synchronous) nesting procedure which allows a rapid setup of a series of embedded domains with increasing resolution. To encompass the whole Canary