Impact of nearshore wind stress curl on coastal circulation and primary productivity in the Peru upwelling system

Coastal upwelling dynamics are strongly affected by alongshore wind stress and nearshore wind stress curl. A coupled physical-biogeochemical regional model and lagrangian diagnostics are used in the Peru current system to determine how the upwelling of nutrients and the primary productivity are impacted by the spatial structure of the nearshore wind stress. Three wind stress products derived from the ERS and QuikSCAT scatterometers and a smoothed QuikSCAT field, mainly differing in nearshore wind stress curl patterns, were used. Simulations are found to produce significantly different mean surface chlorophyll distributions and show that strong upwelling-favorable nearshore wind stress curl may locally induce a wide coastal productive zone through upwelling of nutrient-replete waters brought by a shoaling coastal undercurrent. Using wind stress products with realistic nearshore patterns is therefore crucial for the modeling of coupled physical-biogeochemical coastal processes.