Average Circulation, Seasonal Cycle and Mesoscale Dynamics of the Peru Current System: A modeling Approach.

Pierrick Penven, Jose Pasapera, Jorge Tam, and Vincent Echevin

The Peru Upwelling System is located along then west coast of South America, approximately between 20°S to 5°S and between 90°W to 70°W, where an equatorward wind forces a strong coastal upwelling. With the Benguela Current System, the Canary Current System and the California Current System, the Peru Upwelling System is one of the four major coastal upwelling regions of the world. These four upwelling systems are highly productive. The Humboldt Current Large Marine Ecosystem (i.e. from the South of Chile to the North of Peru) is the most productive marine ecosystem in the world, as well as the largest upwelling system. It produces approximately 18-20% of the world's fish catch (http://na.nefsc.noaa.gov/lme/text/lme13.htm). This production is highly variable and strongly dependent on environmental factors such as sea temperature and currents. In this area, El Niño is a major contributor to environmental variability. In an attempt to investigate the dynamics of the Peru Upwelling System and the coupling between the environment and the ecosystem dynamics, a set of physical models is implemented.

The circulation in the Peru Upwelling System is very complex. Unlike other upwelling systems, the Peru Current System is closely connected to the eastern limit of the equatorial currents. Hence, a model of the Peruvian upwelling should explicitly resolve as well the eastern equatorial dynamics. In this presentation, the focus is on the average circulation, the seasonal cycle and the mesoscale dynamics of the Peru Current System. After a presentation of the characteristics of the model, the modeled annual mean circulation is described. Model/data comparisons are then performed as a first test of the ability of our regional configuration to simulate the seasonal cycle in the Peru Upwelling System. A special attention is brought onto the dynamics of the Peru-Chile Under Current and on the eddy activity which is strongly affected by the closeness of the Equator.