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Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 279-283) / Microfiche. / xvi, 283 leaves, bound ill. 29 cm

No description available.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1984. / Bibliography: p. 325-328.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 67).

Observations from 1995 and 1996 described the seasonal evolution of the threedimensional density field in the western Irish Sea. A cold, dense pool flanked by strong nearbed density gradients was present from May until October. Temperature had the dominant effect on density from June onwards. The trajectories of 55 satellite-tracked drifters defmed the full spatial extent of the cyclonic circulation that is the western Irish Sea gyre. Several distinct recirculation paths were observed and drifter speeds were in good agreement with geostrophic calculations based on the observed density field. The existence of such organised, baroclinic flows in shelf seas demands that coastal ocean models should reproduce their dynamics correctly, if the models are to be useful as environmental management tools. One such model, ECOMsi, was applied to the study area and results from seasonal simulations were compared with the observations. A new technique was developed to perform quantitative comparisons between modelled and observed flow fields. The model successfully reproduced the three-dimensional temperature structure throughout the seasonal simulations, and also predicted the cyclonic, near-surface residual circulation of the gyre. The model demonstrated conclusively that the gyre is density-driven and revealed the same recirculation paths that were visible in the drifter tracks. The vertical structure of the modelled density-driven flow confirmed the geostrophic nature of the currents and emphasised the important dynamical role of sharp density gradients near the bed (bottom fronts). A quantitative comparison of different model runs identified the critical parameterisations and forcing quantities for this application. An accurate specification of air temperature over the sea region was required for the model to achieve the correct timing of the stratification breakdown. During this phase, convective cooling at the surface was seen to be as important as the mixing by autumnal winds in eroding the density structure. The possibility of a seasonal reversal in density-driven flow along the east coast of Ireland was also identified. A new interaction between the wind and the density field, which could defme where the strongest currents in the gyre are to be found, is described. The model is now considered to be sufficiently well tested to use in a predictive capacity and for biological transport studies. This work highlights the benefits that can be obtained using high quality spatial and temporal field observations in the critical testing of numerical models, and furthermore suggests that shelf seas are the perfect location for such tests to be performed.

Baroclinic tides play a significant role in driving deep-ocean mixing, which not only influences the transport of nutrients and other biological tracers, but also affects the large scale circulations. This thesis combines advanced numerical modeling techniques and available observations to investigate the characteristics of baroclinic tides in the Red Sea, and understand their formation and fate, and their influence on the circulation and ecosystem. Based on a validated 3D, non-hydrostatic and high-resolution MIT General Circulation Model (MITgcm), we first established four potential areas for the generation of baroclinic tide in the Red Sea: the Strait of Bab-el-Mandeb (BAM), the southern Red Sea, the Gulf of Suez, and the Strait of Tiran. These areas are consistently suggested by the spatial distribution of baroclinic tidal kinetic energy and energy fluxes. The majority of the baroclinic energy disappears within the basin; either dissipates due to friction and bottom drag or converts back into barotropic energy due to pressure. We next conducted 2D numerical simulations to investigate the generation mechanism behind the formation of the observed internal solitary waves(ISWs) in the southern Red Sea, revealing the dominant role of tide-topography interactions. Instead of evolving from the disturbed thermocline due to a locally impinging tidal beam ISWs are generated from the depression formed near the shelf. As this depression propagates out of the shelf, it gradually steepens and ultimately breaks into a group of ISWs. To further study the breaking and dissipation processes of the ISWs, we implemented a regional high-resolution MITgcm for the southern Red Sea with a realistic topography revealing that the breaking process is triggered by the fission mechanism. The associated particles transport is further quantitatively analyzed, revealing a significant transport, both vertically and horizontally. The thesis, finally examined the tidal influences on the basin-scale circulation of the Red Sea. Comparison experiments with and without tides show that, the intrusion of the Gulf of Aden Intermediate Water (GAIW) in summer is strongly influenced by the tides. It is suggested that tides enforce more turbulence and mixing at the strait, which significantly increase the diffusivity of heat and salinity.