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Internal tides in Dixon entrance Carrasco, Ana
Abstract
Semidiurnal (M2) internal tides are studied in and near Dixon Entrance. Two complementary approaches are presented: a data analysis and a numerical study. The data consist of current records as well as hydrographic profiles. The derived baroclinic velocities represent a considerable portion of the total signal. The baroclinic velocities change little in time and variations in the vertical suggest the presence of a vertical mode. A nonlinear, frictionless, two-layer, finite-difference numerical model forced by a barotropic tidal wave was applied over an idealized topography representing Dixon Entrance. Specifically, Dixon Entrance was modelled as a coastal east-west oriented, shallow channel connected to a deep flat open ocean through a very steep continental slope. Several numerical experiments are presented. The main result the model offers is a possible explanation, in terms of waves, of the generation of internal tides. The passage of long barotropic Kelvin waves travelling north on the the open ocean triggers a baroclinic diffraction process which gives rise to cylindrical Poincare waves travelling towards the deep ocean, westward, Kelvin waves propagating along the coast, northward, and Kelvin waves propagating inside the channel, eastward. This wave pattern was described by Buchwald (1971). The Kelvin wave pattern always seems to be present inside the channel; however, internal waves are very sensitive to variations in the topography, and waves of short wavelengths are also generated. It was possible from the numerical experiments to explain some of the features found in the data analysis. The velocity magnitudes and main generation regions were comparable. The results of the model were unable to explain the detail of the quasi-steady pattern of baroclinic currents.
Item Metadata
Title |
Internal tides in Dixon entrance
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1998
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Description |
Semidiurnal (M2) internal tides are studied in and near Dixon Entrance. Two complementary
approaches are presented: a data analysis and a numerical study. The data
consist of current records as well as hydrographic profiles. The derived baroclinic velocities
represent a considerable portion of the total signal. The baroclinic velocities change
little in time and variations in the vertical suggest the presence of a vertical mode.
A nonlinear, frictionless, two-layer, finite-difference numerical model forced by a
barotropic tidal wave was applied over an idealized topography representing Dixon Entrance.
Specifically, Dixon Entrance was modelled as a coastal east-west oriented, shallow
channel connected to a deep flat open ocean through a very steep continental slope. Several
numerical experiments are presented. The main result the model offers is a possible
explanation, in terms of waves, of the generation of internal tides. The passage of long
barotropic Kelvin waves travelling north on the the open ocean triggers a baroclinic
diffraction process which gives rise to cylindrical Poincare waves travelling towards the
deep ocean, westward, Kelvin waves propagating along the coast, northward, and Kelvin
waves propagating inside the channel, eastward. This wave pattern was described by
Buchwald (1971). The Kelvin wave pattern always seems to be present inside the channel;
however, internal waves are very sensitive to variations in the topography, and waves
of short wavelengths are also generated. It was possible from the numerical experiments
to explain some of the features found in the data analysis. The velocity magnitudes
and main generation regions were comparable. The results of the model were unable to
explain the detail of the quasi-steady pattern of baroclinic currents.
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Extent |
7218491 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-07-03
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0053121
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1998-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.