Physical oceanographic conditions off central south chilean coasts

The Chilean Navy Hydrographic and Oceanographic Service (SHOA), has performed 3 research cruises during 1999. Two of them, consisting of a transect perpendicular to the coast, off 33º S, extended 200 nautical milles from the coast, where 11 oceanographic stations were distributed. This cruises were performed during fall and spring. The third cruise, had place between 34º 45'S and 36º 15`S, from the coast and the 73º 48'W, where 50 oceanographic stations were conducted. In all the stations, temperature, salinity and dissolved oxygen was obtained using a Seabird CTD, and water samples were colected to correct the registered data by the instrument.

The goal of this research is, to conduct an interseasonal comparison of the existing oceanographic conditions off Valparaíso, to describe the physical and chemical parameters distribution in the study area, and to study the spatial behaviour of circulation and mass transport, off the central south coasts of our country. With this objective, temperature, salinity and dissolved oxygen sections were prepared and analyzed, and also, geostrophic velocity sections and dynamic highs maps.

The results due to the analysis performed, show the variability of the Humboldt Currents System at the latitude of Valparaíso, between the conditions found during the cold event developed in the Central Equatorial Pacific during 1998-99, and those detected under its weakening conditions, being observed variations in the flows intensity and in the mass transport level. By another hand, the results from central south Chile, show the features of the Humboldt currents system, in terms of its longitudinal extension, intensity and mass transport, during the period of analysis.