Resumen

PARADA V., Carolina E.; SOBARZO B., Marcus A.; FIGUEROA M., Dante  y  CASTRO C., Leonardo. Circulation of the Arauco Gulf in a seasonal transitional period: A new approach. Investig. mar. [online]. 2001, vol.29, n.1, pp.11-23. ISSN 0717-7178.  http://dx.doi.org/10.4067/S0717-71782001000100002.

ABSTRACT. This study characterizes the circulation patterns in the Arauco Gulf (37°10'S - 36°45'S, Chile) which are associated to the intensification and relaxation of the coastal upwelling, during a summer-autumn transition period. Sea Surface Temperature images (10, 16, 22 and 27 of March), current time series (10 and 28 m depth) from three current-meter moorings, and wind time series were analyzed. The results indicated that semidiurnal tides, diurnal fluctuations of S-SW wind, upwelling and downwelling in the shelf adjacent to the Gulf are important factors that determine the circulation in the Arauco Gulf. The discussion was centered in the 3-10 day oscillations. Four relaxation events (9-13, 19-20, 23-24, and 30-31 of March) and four upwelling events (2-8, 14-18, 21-22 and 25-29 of March) adjacent to the Gulf were identified during the study period. S-SW wind forced a one-layer anticlockwise circulation during the most intense upwelling. In contrast, during N wind, the circulation in the Gulf showed a clockwise trend, associated to downwelling in the region adjacent to the Gulf. In transitional periods or during weak N or S-SW winds, the circulation showed a double layer system: an anticlockwise trend near the surface and a clockwise trend in the subsurface. A conceptual scheme of circulation in the Arauco Gulf is suggested for upwelling-relaxation periods, based in the sub-inertial circulation pattern, and depending mainly on the fluctuations of the wind strength and direction, and on the inflow of water into the Gulf through the "Boca Grande", its main connection with the open sea

Palabras clave : upwelling; wind; SST; coastal circulation; Arauco Gulf; Chile.

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