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The linear and non-linear baroclinic instability in the eastern North PacificLee, Dong-kyu 04 May 1987 (has links)
Using a linear quasi-geostrophic model of large scale spiraling flow and vertical density
gradient in the eastern North Pacific, we evaluate the complex dispersion relationships
for quasi-geostrophic waves. Our calculations indicate that the geostrophic circulation
of the eastern North Pacific can locally convert potential energy to mesoscale
kinetic energy on a scale comparable to the observed space and time scale and should
be a source of eddy energy, distant from the eddies spawned by the Kuroshio and near
the topographic features. But the local growth rates by linear stability analysis do not
relate to the observed features of eddy kinetic energy in the eastern ocean; eddy kinetic
energy increases to the south and has a maximum in the subtropical region.
The non-linear baroclinic instability is analyzed using a three-layer quasi-geostrophic
numerical model. Three experiments with different idealized initial mean
flow are performed. Local energetics are calculated to highlight the difference between
the southward return flow and westward return flow regions. It is found that the
boundary flux of mean to eddy kinetic energy conversion is the main differences
between two regions: it is large in the westward return flow region but is small in the
southward return flow region. Two waves with different characteristics are found: the
short waves (periods of 120 days), that propagate to the west and form several wave
trains parallel to the southern boundary, and the long waves (periods of 200 days),
that propagate to the south-west. These two waves are remarkably similar to the
measurements of open ocean eddies at 28°N and 152°W. It is shown that there are high
eddy activities in the southward return flow regions by influxes of eddies from other
areas, but the southward return flow region is vacant in eddies by outflows of the westward
and south-westward propagating waves. / Graduation date: 1987
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Processes determining silicate concentrations in the northeastern Pacific OceanHager, Stephen W. 13 February 1969 (has links)
Graduation date: 1969
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Structure of the northeast Pacific wave cyclone of 19 November 1980Gratham, Christopher H. January 1991 (has links)
The frontal system that passed over the Storm Transfer and Response Experiment Study area on 19 November 1980 was the third vigorous system in succession to affect this region of the northeast Pacific Ocean. This study marks the first detailed investigation of a frontal wave over the Gulf of Alaska and as such provides structural details not shown in other studies.
Precipitation and changes in temperature, wind velocity, and pressure were associated with the passage of both the warm and cold fronts. The thermal structure exhibits a well defined warm sector with regions of large baroclinicity in both the warm and cold frontal zones. Data from radiosonde releases from the northern-most of two observing platforms indicate a mid-level upper moisture front above the kata cold front. Throughout these northern cross-sections, gradients in the warm and cold frontal zones are of similar magnitudes
while sections from the southern ship show a warm frontal zone that is more intense than the cold transition region. Along-frontal gradients of equivalent potential temperature are of the same order of magnitude as the cross-frontal gradients.
Horizontal wind components relative to the storm indicate strong inflow to the system at lower layers from both south and east. The wind exits the system to the west and south. Upper level winds are westerly throughout. Gradients of wind components are strongest in frontal zones, which results in the cold front coincident with the peak axis in the vertical component of relative vorticity. The field of horizontal divergence also exhibits its largest magnitudes in the frontal zones, with convergence in the warm frontal zone and divergence in the cold transition region. This seldom observed feature of divergence at the cold front leads to a downwelling motion in this region and categorizes the front
as a kata-cold trout. Most of the upward vertical velocity occurs in and around the warm frontal zone as a result of horizontal convergence in this region. Relative isentropic analysis indicates that there are three main air streams within the system. The warm conveyor belt flows to the north in the warm sector and rises gradually as it makes it way to the north. Ahead of the warm front and behind the cold front are two cold air streams that flow to the north and south respectively.
Analysis of the kinematic, frontogenesis indicates that confluence and infrequently studied shear effects are the most important processes influencing the frontal gradients. Analysis of uncertainty in the terms of the prognostic kinematic frontogenesis equations reveals that the diabatic heat and twisting terms that others have found important are smaller than their estimated errors in this study. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
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Gravity and structures of the crust and subcrust in the northeast Pacific Ocean west of Washington and British ColumbiaCouch, Richard W. 08 May 1969 (has links)
Graduation date: 1969
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Gravity and structures of the crust and subcrust in the northeast Pacific Ocean west of Washington and British ColumbiaCouch, Richard W. 08 May 1969 (has links)
Graduation date: 1969
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Acoustic monitoring of earthquakes along the Blanco Transform Fault Zone and Gorda plate and their tectonic implicationsDziak, Robert P. 02 June 1997 (has links)
Hydroacoustic tertiary (T-) waves are seismically generated acoustic waves that propagate
over great distances in the ocean sound channel with little loss in signal strength.
Hydrophone recorded T-waves can provide a lower earthquake detection threshold and an
improved epicenter location accuracy for oceanic earthquakes than land-based seismic
networks. Thus detection and location of NE Pacific ocean earthquakes along the Blanco
Transform Fault (BTFZ) and Gorda plate using the U.S. Navy's SOSUS (SOund
SUrveillance System) hydrophone arrays afford greater insight into the current state of
stress and crustal deformation mechanics than previously available. Acoustic earthquake
information combined with bathymetry, submersible observations, earthquake source-parameter
estimates, petrologic samples, and water-column chemistry renders a new
tectonic view of the southern Juan de Fuca plate boundaries.
Chapter 2 discusses development of seismo-acoustic analysis techniques using the
well-documented April 1992 Cape Mendocino earthquake sequence. Findings include a
hydrophone detection threshold estimate (M~2.4), and T-wave propagation path modeling
to approximate earthquake acoustic source energy. Empirical analyses indicate that
acoustic energy provides a reasonable magnitude and seismic moment estimate of oceanic
earthquakes not detected by seismic networks. Chapters 3 documents a probable volcanogenic T-wave event swarm along a pull-apart basin within the western BTFZ during January 1994. Response efforts yielded evidence of anomalous water-column ��He concentrations, pillow-lava volcanism, and the first discovery of active hydrothermal vents along an oceanic fracture zone. Chapter 4 discusses the detection of a NE-SW trending microearthquake band along the mid-Gorda plate which was active from initiation of SOSUS recording in August 1991 through July 1992, then abruptly ceased. It is proposed that eventual termination of the Gorda plate seismicity band is due to strain reduction associated with the Cape Mendocino earthquake sequence. Chapter 5 combines bathymetric, hydro-acoustic, seismic, submersible, and gravity data to investigate the active tectonics of the transform parallel Blanco Ridge (BR), along the eastern BTFZ. The BR formation mechanism preferred here is uplift through strike-slip motion (with a normal component) followed by formation and intrusion of mantle-derived serpentinized-peridotite into the shallow ocean crust. The conclusion considers a potential link between the deformation patterns observed along the BTFZ and Gorda plate regions. / Graduation date: 1998
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Millennial-scale surface and deep water oscillations in the N.E. Pacific : implications for late pleistocene climate changeLund, David Charles 30 October 1997 (has links)
Graduation date: 1998
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The fall transition of Oregon shelf watersReid, Brad 17 October 1986 (has links)
A long and gradual transition between the summer and winter
oceanic regimes was observed off Oregon during the autumn of 1980.
Hydrographic sections and a single current meter mooring between
August and December show the ocean possessed characteristics during
fall that have not been observed during other seasons: a slow ascension of
the poleward undercurrent and the appearance of a large bottom
boundary layer.
The decay of summer's southward surface flow was achieved by a
series of modest northward wind events during late summer as the effects
of southward winds were becoming diminished. The northward wind
events had progressively stronger influence on surface currents. The
barotropic current fluctuations that are a signature of the summer regime
continued during the transitional period. The weekly-to-monthly
averaged flow was barotropic during much of the transition.
Hydrographic sections and time series of alongshore current shear
and temperature show that the leveling of the frontal layer was achieved
gradually over a two month time scale.
The winter regime was established during eleven days of
continuous northward wind stress in early November. / Graduation date: 1987
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Development of methods to improve knowledge of tritium inputs to the oceanStark, Sheila January 2003 (has links)
No description available.
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The structure and tectonics of the Blanco Fracture ZoneIbach, Darrell Henry 06 August 1980 (has links)
Graduation date: 1981 / Best scan available. Figures in original are black and white photocopies.
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