Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 169-179). Also available on the World Wide Web.

A mathematical model is developed which extends the theory of rip currents developed by Bowen (1969b) for a straight beach to curved beaches where radii of curvature are large relative to the width of the surf zone. Nine forcing terms are found to cause rip current systems. The terms are functions of the longshore variation in wave height and angle of incidence of the incoming waves at the breakers. The model is applied to the case of a circular beach with conical nearshore bottom topography. A large rip current component is found to exist which is inversely proportional to the radius of curvature of the beach. Another significant rip current component is found to be proportional to the variation in the angle of incidence of the waves at the breakers. This component would cause rip currents on a straight beach where some irregular offshore topography caused some variation in the incident angle of the incoming waves. Another component rip current was found which was essentially the same as the one predicted by Bowen (1969b). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis investigates two separate but related problems. In Part I a study is made of the propagation of continental shelf waves and barotropic Rossby waves in a steady, laterally sheared current of the form V + Є W, where W is a centred random function and Є << 1. If the correlation length of W is small compared with the characteristic horizontal length scale of the system; for example, the shelf width or a channel width, the waves are unstable. Their growth rate is largely determined by the magnitude of the correlation length, while the phase speed is given by the sum of weighted averages of the mean current V and the lateral gradient of potential vorticity. Application of the theory to the Brooks and Mooers (1977a) model of the Florida Straits yields wave parameters that are in accord with those measured by Duing (1975). In Part II, an attempt is made to understand the dynamics governing observed low-frequency currents in the Strait of Georgia (GS). A simple two-layer model indicates that the mean currents in GS are probably baroclinically stable. A barotropic stability model implies that a shear instability might be of some importance. However, the analysis of current meter data shows that the velocity components of the fluctuations are either nearly in phase or close to 180° out of phase; this means that the motions are not due to the type of waves considered here. Analysis of the relationship between the winds and currents in both the frequency and time domains implies that the wind may play an indirect role in forcing GS motions. It is conjectured that the wind and tide interact with the Fraser River outflow to modulate the estuarine circulation in the system and force low-frequency currents. Direct nonlinear interaction between tidal constituents produces a coherent fortnightly variation in the currents, but cannot account for the observations. / 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

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Allan J Clarke, Florida State University, College of Arts and Sciences, Dept. of Oceanography. Title and description from dissertation home page (Jan. 13, 2005). Includes bibliographical references.

Thesis (M.S.)--Naval Postgraduate School, 1992. / Cover title. "December 1992." Includes bibliographical references (p. 79-82).

Thesis (M.S.)--Naval Postgraduate School, 1988. / Cover title. "June 1988." Includes bibliographical references (p. 194-202).

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Large beach cusps with wavelengths O(200m), sometimes termed mega-cusps, were measured along 18km of the Southern Monterey Bay coastline from October 2004 to April 2005 to investigate the cuspate shoreline response to rip current systems. Monterey Bay is a unique location for the study of rip current systems, which has with well defined rips that are present all year long, a large dune erosional rate, and incident wave energy that is primarily shore-normal with a large alongshore gradient. Contours of the coastline were extrapolated from the surveys using an all-terrain vehicle equipped with Kinematic GPS. Cusp spacing was inferred from the data using a zero up-cross technique and found to be O(230m) for low wave energy beaches and O(250m) for high wave energy beaches. Migration rates of the cusps were found to be 1-5m/day owing to the quasi-uniform erosion of the dune system. Cusps were found to be semi-permanent features with length scales dependant upon the local wave climate.