The Response of the Northpatagonian Gulfs to Tidal and Wind Forcing

MARIANO H. TONINI; ELBIO D. PALMA

Bahia Blanca, Argentina

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

Instituto Argentina de Oceanografía

The ocean circulation of the Northpatagonian Gulfs is characterized by large tidalamplitudes, high wind speeds and important heat and humidity fluxes from theatmosphere. The dynamical interplay of these forcings leads to the generation of strongfronts with one of the largest biological productivity of the Patagonian Shelf. Weanalize in this study results from a three dimensional non-linear barotropic model of theGulfs forced by winds and tides. The objective is to examine the relative effects oftopography and forcing on the large-scale residual circulation with focus on gyreformation and tide-wind interactions. The model has high resolution (1.5 km) and isforced by seven tidal constituents at the open boundary, and spatially uniform winds atthe surface. There is general agreement between tidal elevations and currents predictedby the model and the available measurements. The spatial distribution of the energy fluxand dissipation of the major tidal constituents are examined in detail. The nonlinearinteraction between the tidal currents and bottom topography leads to the formation ofstrong tidal dissipation near Valdés Peninsula and the mouth of the Gulfs. Wind-drivencurrents are larger and noisier when the tides are absent indicating a strong influence oftidal friction on the wind-driven circulation. The 3D flow fields show significantvertical variations, with strong currents at the surface and weaker return flow at depth.These fluxes in turn generate areas of alternative upwelling and downwelling at thecoast depending on with direction, coastal orientation and bottom topography.