How the Zapiola Anticyclonic circulation dictates the distribution of eddies in the Southwestern Atlantic

MARTIN SARACENO; PROVOST, C.

San Diego

Conferencia; Ocean Surface Topography Science Team Meeting; 2011

Eddies in the Southwestern Atlantic are detected from satellite altimetry data using a modified version of the Okubo-Weiss method. Results obtained are validated against 32 eddies clearly trapped by drifting buoys and by comparison with eddies detected by an expert. Chlorophyll-a images are used as well to support the expert detection. Results indicate that the method successfully detects up to 87% of eddies. Distribution of eddies in the region shows two salient observations: (i) 91% of eddies detected inside the Zapiola Drift (ZD) area are cyclonic and (ii) 61.4% of eddies detected just outside the ZD are anticyclonic. It is proposed that perturbations of the circulation associated to the ZD may generate meanders that, when occurs inside the ZD can detach from the main current and generate a cyclonic eddy. A similar mechanism may explain the higher number of anticyclonic eddies observed outside of the ZD region. The distribution of eddies and the mechanism proposed to explain such a distribution both support the concept that the ZD circulation is strongly controlled by the bottom topography and is eddy driven.