Seasonal Variability of the Oceanic Circulation in the Gulf of San Jorge, Argentina

This study uses a high-resolution model to characterize the seasonal variability of the oceanic circulation in the Gulf of San Jorge (Argentina). The time mean circulation is dominated by a cyclonic gyre bounded by a relatively strong coastal current and, on its offshore side, by the Patagonia Current. The gulf circulation varies significantly with season. Tidal mixing during the summer months generates baroclinic pressure gradients that allow development of a cyclonic gyre in the southern region. During winter, erosion of density gradients weakens the cyclonic tendency and a large anticyclonic gyre develops in the southern region. Atmospheric heat fluxes regulate the transition between summer and winter circulation patterns. Analysis of process-oriented experiments indicates that summer circulation is mainly driven by the interaction between tides and stratification while winter circulation is mainly driven by wind forcing. The mass exchanges between the gulf and the open shelf peak during the summer due to a larger onshore penetration of the Patagonia Current. During winter, these exchanges are very weak and remain largely confined to the northern portion of the gulf.