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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

On the calculation of particle trajectories from sea surface current measurements and their use in satellite sea surface products off the Central California Coast

Spence, Luke J. 12 1900 (has links)
This thesis explores the possibility and feasibility of improving existing satellite measurements of sea surface temperature (SST) by the incorporation of high- frequency (HF) radar-derived surface current data. Water parcels tagged with SST are advected using particle trajectories calculated by integrating surface current velocity data. The SST of these advected water parcels are compared to SST measurements at the final times and locations of the advected water parcels. Different methods of generating surface currents from HF radar measurements are also examined. The Totals current method is a local fitting method which generates surface current measurements by solving a least-squares equation fitting multiple measurements from different radar sites. The Open-boundary Modal Analysis (OMA) method is a global method which fits a series of eigenfunction modes to available radial measurements. These modes are generated by solving two Laplacian eigenvalue problems on the domain with Dirichlet and Neumann boundary conditions, and adding a set of boundary modes to account for flow across open boundaries. Any current field in the domain can be described using a combination of these modes. The two methods are compared for accuracy against an analytic solution to the linear Stommel problem. / NOAA Corps author
32

The subsurface frontal zone beneath the subtropical convergence in the northeast Pacific Ocean

Blanton, J. O. 25 January 1968 (has links)
Graduation date: 1968
33

Comparison of sea level and currents off the Oregon coast using mean monthly data

Marthaler, James Gordon 06 October 1976 (has links)
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
34

Vertical current measurement in the Oregon coastal upwelling region

Deckard, Dennis E. 30 August 1973 (has links)
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
35

A mesoscale study of coastal currents and upwelling off Peru

Enfield, David B. 01 May 1970 (has links)
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
36

The general circulation in the north Pacific Ocean referred to a variable reference surface

McAlister, William Bruce 18 May 1962 (has links)
Graduation date: 1962
37

Observations and analysis of ocean currents above 250 meters off the Oregon coast

Maughan, Paul M. 15 May 1963 (has links)
Graduation date: 1963
38

Bedform evolution under the combined influences of waves and currents at the inner-shelf MISO site /

Blodgett, William C. January 2002 (has links) (PDF)
Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): Timothy P. Stanton, Edward B. Thornton. Includes bibliographical references (p. 71-73). Also available online.
39

Displacement of tethered hydro-acoustic modems by uniform horizontal currents

Thompson, Scott R. January 2009 (has links) (PDF)
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Papoulias, Fotis ; Rice, Joseph. "December 2009." Author(s) subject terms: Acoustic modem, Cable, Steady state, Undersea sensors, Catenary, Mooring. Includes bibliographical references (p. 41). Also available in print.
40

Dynamics of transport and variability in the Denmark Strait overflow /

Girton, James Bannister. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 162-170).

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