OBSERVATIONS OF THE GEOSTROPHIC CURRENT AND WATER MASS CHARACTERISTICS OFF POINT SUR, CALIFORNIA, FROM MAY 1988 THROUGH NOVEMBER 1989

The Point Sur transect (POST) has been occupied 6-8 times per year since 1988 to resolve the flow in the California Current system at seasonal and interannual time scales. The POST extends offshore, normal to bottom topography, along 36-degrees-20'N, to 123-degrees-01.7'W where it doglegs southwest along the California Cooperative Fisheries Investigation (CalCOFI) line 67. Hydrographic observations from seven cruises over 2 years have been used to study variations of alongshore geostrophic velocities and water mass characteristics within these time scales. The California Undercurrent was a prominent feature in six of the seven sections analyzed and was very weak during a period of strong equatorward wind stress. The position of the undercurrent core varied from 12 to 42 km from shore while its strength varied from less than 5 cm s-1 to 35 cm s-1, with the maximum flow occurring in winter. The undercurrent (core) over the continental slope was found from 70 to 460 m depth throughout these seven cruises. The nature of the alongshore geostrophic velocities and the location and spatial extent of the California Undercurrent appear strongly related to specific wind events, both local and remote. Remote wind forcing from the south was believed to cause anomalous, strong poleward flow throughout the entire water column above 1000 dbar during a period of local equatorward wind stress.