Current-meter observations in the Argentine Continental Shelf

The first moored current measurements carried out on the Argentine Continental Shelf are presented. In order to explore the mean value and the main temporal scales of the velocity field, current meter data were collected in a cross-shelf section near 43°S between September 1991 and August 1992. The records indicate that the mean flow is parallel to the local topography and that its intensity increases towards the shelf-break. The mean flow values seem to be related to the interaction of tidal currents with sea-surface height in the inner shelf and cross-shelf variations in the mass field in the middle shelf. The high frequency component (periods of less than 30 h) accounts for more than 80% of the observed kinetic energy. Close to the coast the semidiurnal component is dominant (possibly due to a resonance process), while in the middle shelf the inertial and diurnal components become equally important. The very low frequency component (periods longer than 10 days) increases its energy seaward, which suggests that it might be forced by ocean circulation. The relation between currents in the band 0.5-0.1 cycles per day and the wind measured on the coast is not clear.