Topographic Gyres, Coastal Jets and Fronts in the Northpatagonian Gulfs

ELBIO D. PALMA; MARIANO H. TONINI

Bahia Blanca, Argentina

Conferencia; Science and management of estuaries and coasts (ECSA44); 2008

Estuarine and Coastal Sciences Association

The influence of tidal forcing, heat fluxes and tidal and wind mixing on the circulationand stratification near Valdes Peninsula (VP) and adjacent regions of the San MatiasGulf (SMG) is examined using a 3D high- resolution baroclinic ocean model. In thecontrol run the model is forced by tides and monthly climatological fields of heat fluxes.Additional experiments include the addition of monthly wind fields. It is found that thetide plays an important role in regulating the annual cycle of the circulation in SMG.The overall circulation pattern inside the Gulf is dominated by a strong cyclonic gyreduring summer with smaller anticyclonic gyres on the southwest coast and north of VP.The spinup of the cyclonic circulation between September and January is likely causedby the interaction of the tides and stratification (generated by surface heat fluxes) in thepresence of variable topography. From February to April the northern cycloniccirculation spins down and gradually shrinks in size towards the south. When wintererodes the stratification, the western sector of the Gulf is occupied by an anticyclonicgyre. The inclusion of wind forcing strengthens both the summer (cyclonic) and winter(anticyclonic) circulation but the spatial structure of the gyres is not substantiallymodified. The model also exhibited spring-summer tidal mixing fronts following the60m isobath northeast of VP and over the SMG mouth. Overall, the model results arequalitatively consistent with circulation patterns based on hydrographic observationsand previous low-resolution models of the region.