Graduate Thesis Or Dissertation
 

Inner-shelf circulation off the central Oregon Coast

Público Deposited

Contenido Descargable

Descargar PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/4t64gq77b

Descriptions

Attribute NameValues
Creator
Abstract
  • Inner-shelf circulation and mechanisms of across-shelf transport of water masses were examined using seven years of observations collected by the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) program, a long-term monitoring effort along the central Oregon coast. Since 1998, moored velocity and hydrographic measurements have been obtained during the summer upwelling season in water depths of 30, 15, or 8 m at 3-5 stations along a 75 km stretch of the Oregon shelf. These observations enabled a description of along-shelf variations and upwelling dynamics in an area of intermittent wind forcing but little buoyancy influences. While wind forcing and bathymetry were nearly spatially uniform in the inner-shelf, circulation was spatially variable due to an offshore submarine bank. Classic two-dimensional upwelling existed north of the bank, with bottom stress and acceleration balancing the wind stress in the depth-averaged along-shelf momentum equation. This balance failed onshore of the bank where the pressure gradient and nonlinear advection were needed to close the momentum balance. Driven by along-shelf wind forcing, across-shelf surface transport was 25% of the theoretical Ekman transport at 15 m water depth, 1-2 km offshore, and reached full Ekman transport 5-6 km offshore in 50 m of water. This result, based on season-long comparisons of measured across-shelf transport and theoretical Ekman transport, defines the across-shelf scale of coastal upwelling on the Oregon shelf. However, observations of across-shelf circulation also highlight the rapid movement of water masses and variable residence times in the inner shelf. To quantify the time variability of across-shelf exchange, a numerical model was adapted to estimate vertical eddy viscosity using the velocity measurements. Resulting depth-averaged eddy viscosities ranged from 0.8x10[superscript −3] m [superscript 2] s[superscript −1] during upwelling winds to 2.1x8x10[superscript −3] m [superscript 2] s[superscript −1] during downwelling winds, consistent with previous numerical model results. The difference in eddy viscosities between upwelling and downwelling led to varying across-shelf exchange efficiencies and increased net upwelling over time. These results quantify the structure and variability of circulation in the inner-shelf and have significant implications for ecological processes (e.g., larval recruitment, nutrient availability) in the region.
  • Keywords: eddy viscosity, Ekman transport, coastal upwelling, Oregon, inner shelf dynamics, inner shelf circulation, momentum balances, across shelf exchange
Resource Type
Fecha Disponible
Fecha de Emisión
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Declaración de derechos
Publisher
Peer Reviewed
Language
File Format
File Extent
  • 10061487 bytes
Replaces

Relaciones

Parents:

This work has no parents.

En Collection:

Elementos

Miniatura Título Fecha de subida Visibilidad Acciones
file details Kirincich_dissertation.pdf 2017-08-07 Público Descargar