In this thesis, the phenomenon of flow-topography interaction is considered in the context of two dynamically distinct case studies. In the first study, tidally-driven upwelling is investigated usingfield data collected in Hydrographers Passage (20????S), a narrow, navigable channel in the dense outer reef matrix of the southern Great Barrier Reef, Australia. In the second study, island wake formations at Cato Island (155????32????E, 23????15????S) in the deep, Western Coral Sea are examined using a combination of field data and numerical experiments. The result of the Hydrographers Passage study are of considerable scientific interest since they apply to numerous smaller non-navigable reef-edge passages dotted throughout the southern Great Barrier Reef. Strong, semi-diurnal flood tides flowing through a gap in a distal patch reef system at the shelf break generate strong upwelling, providing a pulsed, semi-diurnal input of nutrients to the reefs offshore of the passage. If stable in the long term, this mechanism could have profound evolutionary implications for large reefal areas in the southern Great Barrier Reef. In the second study, two sets of field observations at Cato Island coincided with conditions of strong (~0.7m s-1), vertically sheared incident currents and weaker (~0.3m s-1), more variable incident flows. The combination of dynamically distinct flow regimes and a tall, steep-sided island penetrating oligotrophic surface waters provides a unique opportunity to investigate the impact of island wakes on hydrographic structure and biological enhancement. Field data indicate that flow disturbances downstream of Cato Island are likely to generate biological enhancement during conditions of eddy shedding and non-shedding wakes. A primitive equation numerical model configured on the basis of field observations faithfully reproduces the key features of both data sets; mechanisms responsible for producing these key features are proposed. Previous numerical studies of island wakes have concentrated primarily on eddy shedding flows. In this thesis, the sub-critical (non-shedding) flow scenario is also considered. It is demonstrated that particle retention in island wakes has a ????hair trigger???? characteristic controlled by incident flow speed. This observation leads to a new proposal to explain the long-standing recruitment problem of biological oceanography.

Graduation date: 1968

This thesis demonstrates that at low frequencies (periods longer than 2.5 days) local currents off the coast of Oregon are closely related to the wind. Wind and current observations made during August and September 1969 are described and compared to demonstrate that a relationship exists; the physics of the interaction is not understood. The data are described as functions of both time and frequency. Spectral analysis shows that wind and current were related at frequencies less than 0.017 cycles per hour and at the diurnal frequency; at other frequencies they are apparently not related. The wind and current were then filtered to suppress frequencies higher than 0.017 cycles per hour; they are shown as functions of time. Comparison of the time series reveals certain features of the relationship between wind and current. The current can be considered to be the sum of two parts: a "response" current, which is related directly to the wind, and a "residual" current which is also variable. The amplitude of the response depends on the amplitude of the wind and on the density profile of the water. The time lag between the wind and the response current was variable; on a few occasions the current led the wind. Both the response and the residual current were generally parallel to the bottom contours. The residual current seems to change during periods when the response current is interrupted, so that short current records are not indicative of the mean flow. / Graduation date: 1971

Using the hydrographic data collected by the ACONA from June 1961 to May 1963, the Oregon coastal front has been examined. Representative sigma-t surfaces were chosen to delineate the front, and changes in position of these surfaces with time were used to obtain zonal flow rates for the frontal and surface layers. From May to early October upwelling resulted in offshore flow. Onshore flow was indicated from late October to January, and indeterminate zonal flow occurred during the remainder of the year. Flow within the front agreed with these surface flows in ten of the fourteen observational periods. / Graduation date: 1964

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Restricted until November 2001. Bibliography: leaves 140-147.

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Graduation date: 1991

Graduation date: 1981