Seasonal Variability of the Geostrophic Velocity and Water Mass Structure Off Point Sur, California
Abstract
The Point Sur Transect was established in 1987 by the Department of Oceanography at the Naval Postgraduate to further the present understanding of long term variability of current and temperature in eastern boundary regions. Seven of these cruises were selected for seasonal comparisons of alongshore geostrophic velocities and water mass characteristics. Geostrophic velocities were referenced to the 1000 decibar surface based on available PEGASUS observations. Anomalies of spiciness calculated as deviations from an average offshore T-S profile have been used to identify the location and spatial extent of the eastern Pacific water masses. The California Undercurrent (positive spiciness anomaly) was a prominent feature in 6 of the 7 sections analyzed, and was very weak during a period of uncommonly strong equatorward wind stress. The position of the core varied from 12 to 42 km from shore while its strength varied from 10 to 35 cm s, with the maximum flow occurring in winter. The vertical extent of the Undercurrent core covered a region of the continental slope from 70 to 460 m throughout these seven cruises. The nature of the alongshore geostrophic velocities and the location and spatial extent of the 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 during a period of local equatorward wind stress, while an intrusion of warm, salty water was believed to cause a deep penetration (to 700 m) of the California Current in winter.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1990
- Accession Number
- ADA241374
Entities
People
- Timothy D. Tisch
Organizations
- Naval Postgraduate School