Alongshore sub-thermocline variability in the central California Current system
Loading...
Authors
Hicks, Michael R.
Subjects
California Current
California Undercurrent
Coastal trapping
Monterey Bay Meander
California Undercurrent
Coastal trapping
Monterey Bay Meander
Advisors
Ramp, Steven R.
Date of Issue
1992-12
Date
December 1991
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Moored current meter observations were made along the central California continental slope from P. Piedras Blanca to the Farallon Islands. The study area covers an alongshore distance of approximately 290 km and examined the data from off Pt. Piedreas Blancas (P4), Pt. Sur (P2 and P3), Monterey Bay (MB1 and MB@) and the Farallon Islands (D and E). Time and frequency domain analyses were performed on three time segments that included data from combinations of the above mooring locations based on common time periods and depths (350 m - 500 m). Segment 1 revealed a mean poleward flow attributed to the California Undercurrent at all moorings. Segment 2 had a similar mean poleward flow but also exhibited an equatorward reversal at periods between 19.5 and 58.5 days at P2 and MB2 that was less apparent at P3 further offshore and appeared to be coastally trapped. Observed wavelengths were compared to the simple wave theory indicating that the observed signal may have resulted from a combination of two theories i.e. a coastally trapped wave. The complex bottom topography between Pt. Sur and the Monterey Bay prohibited more rigorous comparison between theory and the observations. Satellite sea surface temperature imagery during Segment 3 showed an anti-cyclonic meander with a 65 km radius outside of the Monterey Bay. Current and temperature records at P2 and MB2 indicated that the surface feature's position varied and influenced the currents at depths down to 500 m. Time domain empirical orthogonal functions were calculated for alongshore and across-shore components separately. The first two empirical modes accounted for between 81% and 86% of the alongshore variance in all segments and were attributed to the mean California Undercurrent influence (mode1) and to the deviations from the mean state (mode 2). The first two across-shore modes explained between 66% and 81% of the variance and consistently demonstrated opposing current structures between the Pt. Sur and Monterey Bay moorings, likely due to the Monterey Bay meander influence.
Type
Thesis
Description
Series/Report No
Department
Oceanography
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
111 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.