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Observation and analysis of shear instability in the Fraser River estuary Tedford, E. W.; Carpenter, J. R.; Pawlowicz, Rich; Pieters, R.; Lawrence, Gregory A.
Abstract
We investigate the occurrence of shear instability in the Fraser River estuary. Instabilities observed with an echo sounder are compared with a linear stability analysis based on observed velocity and density profiles. We find that each set of observed instabilities coincides with an unstable mode predicted by the Taylor-Goldstein equation. Each of these instabilities occurs in a region where the gradient Richardson number is less than the critical value of 1/4. Both the Taylor-Goldstein predictions and the echo soundings indicate the instabilities are concentrated either above or below the density interface. This “one sidedness” is in contrast to the archetypal Kelvin-Helmholtz instability. Although the dominant source of mixing in the estuary appears to be caused by shear instability, when the tide produces strong near-bed velocities, small-scale overturning due to boundary layer turbulence is apparent throughout the depth. An edited version of this paper was published by AGU. Copyright 2009 American Geophysical Union.
Item Metadata
Title |
Observation and analysis of shear instability in the Fraser River estuary
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Creator | |
Publisher |
American Geophysical Union
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Date Issued |
2009-11
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Description |
We investigate the occurrence of shear instability in the Fraser River estuary. Instabilities observed with an echo sounder are compared with a linear stability analysis based on observed velocity and density profiles. We find that each set of observed instabilities coincides with an unstable mode predicted by the Taylor-Goldstein equation. Each of these instabilities occurs in a region where the gradient Richardson number is less than the critical value of 1/4. Both the Taylor-Goldstein predictions and the echo soundings indicate the instabilities are concentrated either above or below the density interface. This “one sidedness” is in contrast to the archetypal Kelvin-Helmholtz instability. Although the dominant source of mixing in the estuary appears to be caused by shear instability, when the tide produces strong near-bed velocities, small-scale overturning due to boundary layer turbulence is apparent throughout the depth. An edited version of this paper was published by AGU. Copyright 2009 American Geophysical Union.
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Genre | |
Type | |
Language |
eng
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Date Available |
2011-05-31
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0041944
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URI | |
Affiliation | |
Citation |
Tedford, E.W.; Carpenter, J.R.; Pawlowicz, Rich; Pieters, R.; Lawrence, G.A. 2009. Observation and analysis of shear instability in the Fraser River estuary. Journal of Geophysical Research Oceans 114(11) C11006
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Peer Review Status |
Reviewed
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Scholarly Level |
Faculty
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Copyright Holder |
Pawlowicz, Rich
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International