Graduation date: 1968

Sea level and current data collected near Newport, Oregon are compared to determine an empirical relationship from which the low frequency (f < .1 cpd) alongshore current field over the continental shelf is estimated from observed sea level measurements at the coast. Regression analysis of the near-surface (20-25 m) currents with sea level indicates the surface currents are in geostrophic balance with the sea surface slope. Analysis of the alongshore shear between the near-surface and deep (75-80 m) layers with sea level shows the thermal wind relationship holds. A near-surface regression model is developed from which the mean monthly alongshore current 20-25 m below the surface can be estimated with a standard estimate of error (σ[subscript ER]) less than six cm/sec. The annual range at this depth is nearly 60 cm/sec. A regression model for the alongshore shear is formed from which the mean vertical shear is estimated with a σ[subscript ER] of .07-.10 cm/sec/m. The annual range is approximately .8 cm/sec/m. The surface currents are found to be predominantly driven by the local meteorological conditions. Deep and near-bottom current observations suggest the deep layer currents are primarily influenced by the thermal wind relationship and the location of the California Undercurrent. / Graduation date: 1977

Direct measurements of vertical water motions were made in the Oregon coastal region during the 1972 summer upwelling season. The instruments used were the Webb-Voorhis vertical current meters which are freely drifting neutrally buoyant floats capable of sensing vertical motion. It was found that in the region studied, water tended to sink at depths of 40 to 60 meters under the influence of strong northward and southward winds but that water tended to rise during the slackening periods of a southward wind. Techniques used in processing the data, some problems encountered, and the results of four good dives are presented along with possible correlations of vertical water movements with wind, sea Level, and isopycnal movements. / Graduation date: 1974

Moored instrument records, drogue displacements, and hydrographic observations are used in describing the coastal currents and upwelling off Peru. The data were obtained over the continental shelf near 15°S. during a two week study in late March and early April of 1969. First order statistics and graphical representations of current meter time series indicate that the longshore flow was poleward during most of the study period, interrupted by a three day 'event' of equatorward flow. The similarity of flow at all current meters indicates that the field of flow as quasi-barotropic. The depth, extent, and transport of poleward flow indicated by current meter time series and geostrophic sections were similar to those described in the literature for the Peru-Chile Undercurrent. The observations suggest that this flow moved further offshore as equatorward flow appeared over the shelf. Power spectral analyses performed on current meter records indicate the existence of semidiurnal tidal currents in the longshore direction. The magnitude of these currents is estimated at 10% to 15% of period mean speeds. Ten meter drogue displacements are compared with 25 m recorded currents and with winds. The observations indicate that: the drogues were affected by both the 25 m flow and the wind; the depth of the wind drift layer was between 10 m and 25 m; the drogue displacements were in the sense expected from the Ekman model. Vertical sections of sigma-t, oxygen, and nitrate indicate the existence of conditions consistent with upwelling. Surface maps of temperature, nitrate, and chlorophyll 'a' over the shelf are used to define the horizontal field of upwelling and its variations in time. The distributions suggest that upwelling existed throughout the period and underwent temporal and spatial modulations in intensity. The possibility of a causal mechanism between observed current and upwelling variations is examined. Vertical salinity sections indicated the presence of a weak salinity minimum between the surface and 100 m. It is suggested that this minimum manifests the remnants of a tongue of Subantarctic Water embedded in a much larger mass of Equatorial Subsurface Water. The occurrence of the minimum only in conjunction with poleward flow suggests that the water was advected or mixed coastward somewhere north of the area studied, was entrained in the Peru-Chile Undercurrent, and was carried south again. / Graduation date: 1970

Graduation date: 1962

Graduation date: 1963

Nearly three months of current meter records from five moorings off the Oregon coast taken between October 1977 and January 1978 were analyzed for near-inertial motions. The moorings were located from the midshelf out to the foot of the continental slope, spanning the continental margin. All but two of the eleven current meters were continuously below the mixed layer. For spectral analysis, the current observation period was divided into two time periods, one with large amplitude near-inertial motion (41.1 cm/sec maximum of the band-passed records) throughout and the other with much less near-inertial energy. The spectra of the current meter records showed between a 1 and 6% increase in frequency of the near-inertial peak above f (= 0.0592 cph) in all but three cases. The exceptions showed spectral peaks about 14% below f and were linked to a Doppler shift. The period of large amplitude near-inertial motion had diagonal coherence scales of over 450 meters vertically and 115 kilometers horizontally. An east-west (cross-shelf) wavelength of about 50 kilometers was estimated directly from the phase differences between current meters with roughly horizontal separations. The observed response of a current meter about 35 meters below the mixed layer to sharp maxima in the wind stress was similar to that predicted by the Pollard and Millard (1970) model for wind forced near-inertial motions in the surface mixed layer. The winds associated with a series of atmospheric fronts were apparently responsible for generating a 14-day period of large amplitude near-inertial motion observed below the mixed layer. / Graduation date: 1982

Theoretical studies of two problems concerned with the surface forced, large-scale motions in bounded oceanic regions are presented. In Part I, such motions are considered for a particular area of the North Pacific Ocean known as the Subarctic Pacific Region. Discussion is based on the assumption that the velocity components may be separated into a time-averaged or quasi-steady flow about which fluctuations occur in the form of transient planetary waves. Some of the characteristics of the latter are briefly outlined. Several aspects of the time-averaged motions are then considered. A simple circulation, driven by the vertical velocity structure, is presented for the interior region of the ocean below the upper frictional layer. Also, using observational data to obtain the depth of the layer between the suface [sic] and the main halocline, this upper layer is found to behave as a geostrophic layer of fluid when averaged over many years. Combination of the above observed depths with the mean calculated Ekman divergences permitted calculation of a mean eddy coefficient of diffusivity for density. The results agree very well with those obtained by Veronis for similar oceanic situations. An explanation for the variations in the intrusion of 'warm' water along the top and bottom of the halocline off the coast of British Columbia is also given. The two final sections of Part I deal with the overall, quasi-steady circulation of the Subarctic Pacific Region. Here, a theoretical study is combined with the mean-monthly values of the calculated surface forcing. Curvilinear coordinates are used in order to model the northern boundary formed by the Aleutian-Komandorski island chain. The interior quasi-steady flow, which satisfies a Sverdrup-type balance of vorticity, is closed to the north by a frictional boundary layer. Using mean-monthly values for the surface winds over the region, the observed separation of the eastward flowing West Wind Drift into a northern and southern tending flow is found to correspond to the zero of the mean wind-stress curl. In the northern boundary layer, the characteristics of the westward flowing boundary current there, are shown to change downstream from a Western' to a 'zonal', type boundary current. The stability of the latter is dependent upon vorticity of appropriate sign being added to the boundary layer flow to balance that generated by friction along the coast. Discussion is also given for the effect of passes between the Aleutian islands on the zonal boundary current. Through a type of boundary layer 'suction' or, alternately, by mass transport into the boundary layer, the effect of these passes would seem to be to keep the boundary flow attached to the coast. Finally, spectral analysis of the wind-stress curl data, obtained from the mean-monthly surface pressure, is performed to determine its frequency distribution. A demodulation technique is used to determine the time variations of six of the frequency bands obtained in the spectral analysis. These results are then applied to the circulation in the Subarctic Pacific Region in an attempt to relate variations and spatial distribution in the circulation with the applied winds. The generation by the atmosphere of a type of long, boundary waves, known as Kelvin waves, is considered in Part II. In particular, it is shown that for a general large-scale distribution of wind and pressure systems that only the longshore component of the wind-stress and pressure can generate such waves. Examples are presented for a semi-infinite wind and moving pressure pattern. Kelvin waves are shown to move away from the force discontinuities at the speed of shallow-water waves. These waves are further found to exhibit a frequency shift, typical of non-dispersive waves from a moving source. Using some observed parameters for the atmospheric forcing terms off the Oregon coast of the United States, numerical values for the wave amplitudes for both examples are given. Part II has been published in the form presented here. Reference: J. Fluid Mech. C1970), 42C4), 657-670. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 62-69). / ix, 69 leaves, bound ill., maps 29 cm

The upwelling and cross-shelf transport dynamics along the Pacific Eastern Boundary is explored using a high resolution ocean model for the last 60 years. Three ocean circulations have been modeled. From North to South, we investigate the dynamics of the Gulf of Alaska (GOA), the California Current System (CCS) and the Humboldt Current System (HCS, also known as the Peru-Chile Current System). The statistics of coastal waters transport are computed using a model passive tracer, which is continuously released at the coast. By looking at the passive tracer concentration distribution, we find that the Pacific Decadal Oscillation modulates the coastal variability of the GOA, the North Pacific Gyre Oscillation controls the upwelling of the CCS, while the El-Niño Southern Oscillation affects the upwelling of Peru and Chile mainly through coastally trapped Kelvin waves. Results also emphasize the key role of the mesoscale eddies in the offshore transport of coastal waters masses. The passive tracer experiments, performed in this study in the GOA, CCS, and HCS, therefore could provide a dynamical framework to understand the dynamics of the upwelling/downwelling and offshore transport of nutrient rich coastal water and to interpret how it responds to atmospheric forcing. This also could reinforce our interpretation (and therefore predictions) in the changes in vertical and offshore advection of other important biogeochemical quantities, essential in understanding ecosystem variability.