UC San Diego

Eastern Boundary Upwelling Systems (EBUSs) are sites of enhanced productivity and globally significant fisheries. Instabilities of the upwelling front lead to intense mesoscale features that stir hydrographic and biogeochemical gradients and transport nutrients and organic carbon offshore into oligotrophic waters. These mesoscale features interact, with lifetimes of weeks to months. Here, we use 31 years of daily remotely sensed data to explore whether there are sites and times of predictably enhanced across-shore transport in the California Current System EBUS. By calculating monthly average flow fields, we remove the random mesoscale motions to reveal persistent flow patterns. Locally intensified offshore flows were associated with a coastal jet and two coastal eddies. These features appear to be topographically controlled. Identification of these persistent sites of offshore flow will improve our understanding of the temporal and spatial distributions of nutrient and organic carbon fluxes, and the structure of pelagic ecosystems.