Thesis--Hamburg. / Summary in German. Bibliography: p. 85-91.

Thesis (Ph. D.)--University of Delaware, 2005. / Principal faculty advisor: Victor V. Klemas, College of Marine Studies. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 172-178).

Parameterization of diapycnal mixing is required for accurate modeling of ocean circulation. Almost 50% of all warm Atlantic water flowing towards the Arctic and more than 20% of the returning cold water passes through the Faroese Channels. Diapycnal mixing in the Wyville Thomson Basin (WTB), at the centre of the Faroese Channels, removes heat from Atlantic water flowing northwards and preconditions the cooler waters flowing south over the Wyville Thomson Ridge (WTR). Direct measurements of the dissipation rate of turbulent kinetic energy (epsilon) were obtained from the WTB in September 2007 along with CTD, LADCP and mooring data. Microstructure profiles to a depth of 800m were used to estimate diapycnal diffusivity from epsilon. Large values of epsilon (10-5 Wkg-1) were observed and diffusivity (10-2m2s-1) calculated at approximately 500m depth in a water column depth of 900m. Elevated values coincided with a very strong thermocline between surface Atlantic and cold deep waters in the WTB. Oscillations within mooring data show large O (100m) vertical displacements of the thermocline with a semidiurnal period, hence generation and breaking of tidally forced internal waves by interaction with the ridge topography is proposed as an explanation for observed high diffusivity. Non-hydrostatic 2D model data are used to explore generation and breaking mechanisms of such waves and it is shown that the WTR is an effective generator of internal tides and furthermore that baroclinic energy is trapped and dissipated within the WTB. Conservative calculation of a basin-wide diffusivity (2.51 x 10-4 m2s-1) exceeds that required to maintain global ocean circulation, but heat flux into the dense layer (~14 Wm-2) is found to influence the Faroe-Bank Channel outflow volume by <2%.

Observational data are analyzed and decomposed to reveal internal ocean waves and their interactions with one another. Particularly, the interaction of small-scale internal waves with a large inertia wave packet is examined. Using the governing internal wave equations, an analysis is made of the energy propagation of a small scale internal wave with a large-scale inertia wave. With that, an assessment is made of the frequency of occurrence of various encounter types. Next, the possibility of energy transfer during an interaction is explored. The relative energy of the small wave before interacting with the large-scale inertia wave is calculated and compared to the relative energy during and after the interaction. Performing this analysis on multiple wave-wave interactions seen within the observational data set provides a look into the behavior of these wave types. Additionally, the dissipation within each of the corresponding time-space regions is calculated, giving an alternative explanation other than energy transfer among waves for the disparity in energy. Dissipation estimates and energy results are extrapolated to create a general energy transfer and dissipation estimate in the ocean resultant from these interaction types. A two dimensional non-linear method presents a comparison between the observational data findings and the expected computed result. From there, conclusions are drawn synthesizing the results from the observational and numerical analyses. It was concluded that for observational small waves propagating in the same direction as the background shear, a loss was seen in the wave's energy. For interactions wherein the small wave propagated in the opposite direction, the observational small wave energy increased through the interaction. Within the numerical findings, the small wave energy in same direction interactions was partially lost while the small wave energy in opposite direction interactions was both lost and gained depending on the encounter type which encounter types could be confirmed in observations. The dissipation analysis showed the greatest dissipation during the interaction between a small wave and background shear so the gains seen occurred when the types of encounters expecting a gain were present.

Upper layer temperature in the western Philippine Sea near Taiwan was sampled using a coastal monitoring buoy with fifteen themistors attached from July 28-August 7, 2005. Internal waves and internal solitons were identifed during the empirical orthogonal function analysis. Without the IW and IS, the power spectra, structure functions, and singular measures (respresenting the intemittency) of the temprature field satisfy the power law with multi-scale characteristics at all depths. The IW does not change the basic characteristics of the multifractal structure. However, the IS changes the power exponent of the power spectra drastically, especially in the low wave number domain. It breaks down the power law of the structure function and increases the intermittency parameter. The physical mechanisms causing these different effects need to be explored futher. The Comprehansive Acoustic Simulation System was applied to determine how the IS affect the mines detection by computing the transmission loss (TL) and the ray traces of rand-dependent and range independent cases during the IS period. The maximum TL difference is 20 dB. As a result, the mine detection probability will dramatically be reduced to 1% of the original detection probability.

A new buoyant jet model is presented in this thesis to simulate the trajectory and dilution of a fluid from a single port or line source. The new features include: A generalised derivation of the governing equations so that buoyant jets discharged from a source of any shape can be modelled within the one framework, and the effects of high-frequency internal waves on the motion of the buoyant jet. Past buoyant jet models were constructed for specific cases and their application is necessarily restricted. In this thesis, a new model is developed in a Lagrangian framework that can be applied to buoyant jet discharges at any angle into ambient waters that may be stratified or unstratified, flowing or stagnant. The model is validated using both laboratory and field data. Furthermore, the model is applicable to the continuous discharge of a buoyant jet from line, axisymmetric or elliptic sources and to the instantaneous discharge of a spherical puff. No previously published model is capable of unifying and solving all of these problems within the one framework. Transforming the governing equations to their non-dimensional form shows that the trajectory and dilution of discharges from line or axisymmetric sources or of spherical puffs into a flowing, stratified ambient environment are uniquely specified using three parameters. These are: the non-dimensional size of the outlet port, the relative importance of the initial fluxes of momentum and buoyancy, and the number of orthogonal planes through which entrainment can occur. This is a significant advance in the understanding of the processes affecting buoyant jets. When high-frequency internal waves are present in the receiving waters they can have significant effects on the buoyant jet. These effects are incorporated into the present model. Using data obtained from an experiment conducted off Sydney the effects of internal waves on the height of rise and dilution of the buoyant jet were found to exceed a factor of two. Consequently, it is important that the effects of internal waves (when present) be incorporated into any buoyant jet model.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / Supervised by Erik Mollo-Christensen. Vita. Includes bibliographical references (leaves 217-223).

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1982. / Vita. Bibliography: leaves 321-326.

Thesis (Ph. D.)--Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 1982. / Vita. Includes bibliographical references (p. 217-223).