Assessing the energetic interactions of subtidal flow on the continental slope in an Eastern boundary region
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Authors
Tisch, Timothy Daniel
Subjects
California Current
California Undercurrent
Eddy potential energy
Energy time series
Spectral analysis
Energetic events
California Undercurrent
Eddy potential energy
Energy time series
Spectral analysis
Energetic events
Advisors
Ramp, Steven R.
Date of Issue
1992-12
Date
December 1992
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Seventeen-month time series (May 1989 - October 1990) of current, temperature and conductivity were obtained from 100, 300 and 500 m depth at site P2, located on the 800 m isobaths off Point Sur, and one-year time series (May 1990 - May 1991) of the same variables at similar depths were obtained from site P3, approximately 25 km father offshore on the 1800 m isobath. Results show that no net growth or decay of eddy potential energy (EPE) occurred at wither mooring during their respective deployment periods. At mooring P2, baroclinic instabilities within the water column were signaled by downgradient horizontal eddy heat fluxes that converted mean potential energy (MPE) to EPE at both 225 and 425 m. The dominant balance at 225 m was between mean flow advection (source) and upward eddy heat fluxes (EPE to eddy kinetic energy, EKE), with additional losses coming from downstream advection by the eddy flow. At 425 m, the dominant balance was between downgradient eddy heat fluxes (source) and downstream advection by eddy flow (sink). Unlike 225 m, vertical eddy heat fluxes at 425 m were a weak source (EKE to EPE) while mean flow advection was negligible. At P3, the net balance involved only downward eddy heat fluxes (source) and downstream advection by eddy flow (sink), as mean advection and MPE-EPE conversions were negligible. Analysis of energetic events within the time series of terms in the EPE equation did not reveal any canonical or common pattern which would explain the temporal means described above, but suggest the flow in this region is highly variable. In fact, most events magnitudes of terms were anywhere from 1o to 200 times that of the associated temporal mean. Events at P2 involved both horizontal and vertical processes and had longer time scales (several days to weeks) compared to those at P3, which had much shorter time scales and appeared to involve vertical processes only.
Type
Thesis
Description
Series/Report No
Department
Oceanography
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
207 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.