Circulation processes on the San Pedro shelf

Abstract

Moored current and temperature measurements on the San Pedro shelf show that the circulation has three major components. The sub-tidal currents are primarily a result of slope circulation processes including the California Counter Current and poleward Undercurrent. Fluctuations have characteristic periods of 10 to 30 days with magnitudes decreasing from the shelf-break shorewards. Persistent sea-breezes force sub-inertial clockwise rotary current fluctuations on the outer shelf with a one-day period. These are present throughout the year with the highest amplitudes in summer. These fluctuations decay rapidly with depth. Tidal currents are predominantly semidiurnal. They are barotropic and aligned with the isobaths near the coast, but at the shelf break, there is evidence of internal tide generation with cross-isobath flows near the seabed.