Lagrangean measurements in the San Matias Gulf, Argentina

MARTÍN, SARACENO; F.J, BERON-VERA; J, OLASCOAGA; J.F., SAAD; G., SVENDSEN; TONINI MARIANO HERNAN; G., WILLIAMS; RAÚL, GONZALEZ; M., SORIA; T., BROCHADO; N., AUBONE

Montreal

Congreso; 27th IUGG General Assembly; 2019

The International Union of Geodesy and Geophysics (IUGG)

The San Matías Gulf (GSM) is the most extensive of the northpatagonian gulfs, located between the parallels 40.7oS and 42.2oS in the continental shelf of Argentina. It presents physiographic and environmental characteristics that define it as a semi-enclosed basin with limited water exchange with the adjacent platform. This fact translates into an increase in salinity during the summer months with relevant implications in the thermohaline circulation in the gulf and in the adjacent platform. The particular circulation within the gulf also has a strong impact in determining fishing zones and distribution of marine biodiversity. The knowledge of the circulation in the gulf is however limited to the results induced by sporadic hydrographic measurements, satellite measurements and results of numerical models. This paper presents an analysis of the first trajectories obtained by five Lagrangean drifters launched in the northern part of the GSM. The trajectories obtained follow, at first order, the closed curves of potential vorticity, i.e. confirmed the presence of a closed circulation cell of approximately 70km in diameter centered on 41.4oS, 64.5oW, in good agreement with previous studies. The drifters also highlighted the role of tidal currents in the gulf and showed speeds of up to 70cm/s, suggesting that the dissipation of kinetic energy in the gulf is very high. Near the west coast, complex circulation patterns were evident, including recirculation cells that could have important consequences for the ecology of local species.