File:Variability of the California Current System off Point Sur, California from April 1988 to December 1990 (IA variabilityofcal1094539740).pdf

The Point Sur Transect was established in 1987 by the Department of Oceanography at the Naval Postgraduate School in order to further understand the nature of poleward flows in the California Current System (CCS). The POST extends offshore, perpendicular to bottom topography along 36 deg 20' N to 123 deg 01.7W where it meets and coincides with the California Cooperative Fisheries Investigation (CalCOFI) line 67. The sampling scheme along the transect consists of 22 CTD stations and is approximately 215 km in. length. POST was occupied 19 times from April 1988 to April 1991. Data from 15 of the 19 cruises were selected in order to determine the temporal and spatial variability of the CCS off Point Sur. PEGASUS data as well as hydrographic data and NOAA 11 AVHRR satellite imagery were utilized for comparison. The CUC was observed with speeds in excess of 20 cm/s throughout the year. Mean speed and depth of the CUC was 10 cm s-1 and 100 m respectively, 33 km offshore. The CC was found to have a semi-permanent onshore meander located 150 km offshore. Maximum speeds of this meander were in excess of 20 cm s-1. Mesoscale variability was a dominant feature along POST. Meanders of the CC and the CUC, anticyclonic eddies and cyclonic eddies were all present during this study. Anomalously deep poleward flow was observed along POST. This flow appeared during all seasons with speeds in excess of 10 cm s-1 to depths of up to 2000 m. Geostrophic velocity calculations agreed favorably with PEGASUS derived absolute velocities except during the upwelling season. Reasons for the disparity include; the selection of 1000 m as the level of no motion and surface wind stress. The variability of the CCS was determined to be interannual rather than seasonal. The short duration of this data set, when compared to earlier geostrophic studies, and the absence of upper slope and shelf velocity data may account for the absence of a significant seasonal signal.