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Thesis (Ph. D.)--Oregon State University, 1963. / Typescript. Includes bibliographical references (leaves 53-55). Also available on the World Wide Web.

Graduation date: 1984

Observations between 20 and 40 m depth were made with a towed thermostor chain in the North Pacific. Despite the rapid vertical variation of buoyancy frequency, spectra of isotherm displacements are in fair agreement with other observations and with the Garrett-Munk model. The spectra show evidence of a shoulder and break in slope at a wavelength of 1 km. There is no evidence of significant variation of spectral levels as a function of buoyancy frequency, tow direction, or wind speed. A peak at a wavelength of 1 km in coherence spectra between pairs of isotherms separated in the vertical suggests that internal wave energy at this wavelength is dominated by the low modes. / Graduation date: 1979

Graduation date: 1976

Graduation date: 1983 / Best scan available for figures.

A time-dependent, spectral, barotropic model and a similar two-layer primitive equation model are developed to investigate the planetary-scale wave responses to various types of large-scale forcing: vorticity and heat sources, and sea surface temperature (SST) anomalies. Both models are linearized about the zonal mean states of January climatology. The characteristics of forced Rossby waves are extensively studied based on both the barotropic model experiments and the theory of Rossby wave propagation on the sphere (Hoskins and Karoly, 1981). In particular, both model and theoretical results show that the responses are dominated by ultra-long wave components (zonal wavenumber m = 1, 2, and 3), and that the large responses occur for vorticity sources located at the subtropics and at the high latitudes near 45°N. The model experiments for the wavenumber-dependent sources located at various latitudes show that the ultra-long waves behave like a north-south seesaw between the high and middle latitudes (m = 1) or between the high latitudes and subtropics (m = 2). The north-south seesaw of zonal wavenumber 1 component is in good agreement with that observed by Gambo and Kudo (1983). The responses of long waves (m > 3) are, however, localized in the source regions with relatively small amplitudes. The characteristics of baroclinic responses to prescribed heat sources located at various latitudes are also examined. Over the source latitudes baroclinic responses are dominant; however, the remote responses have a barotropic structure. The north-south seesaws appearing in the barotropic model are also observed in the baroclinic model. A series of baroclinic model experiments, in which surface heat fluxes and internal heating are computed in terms of the model variables, are also conducted to investigate the linear effect of sea-surface temperature (SST) anomalies on the atmospheric circulation. The experiments for prescribed SST anomalies, taken equal to twice those of Rasmusson and Carpenter (1982), simulate many aspects of the associated observed atmospheric anomalies, and suggest, therefore, that a large part of the atmosphere's responses occur via linear dynamics. It is also suggested that the rather weak responses in the North Pacific are due to the lack of a zonally varying basic state. In the case where the SST anomalies are located in the middle latitudes, the responses are about five times smaller than for the tropical SST anomalies. This result is also fairly consistent with the GCM experimental results by Chervin et al. (1976). Subsequent experiments, using climatological January SSTs in the tropics, suggest that the tropical Pacific SST can be an important factor in maintaining the climatological standing waves, at least over the western half of the Northern Hemisphere. / Graduation date: 1984

Graduation date: 1977

Two types of linear random wave simulation methods are investigated; viz., (1) Deterministic Spectral Amplitude (DSA) and (2) Nondeterministic Spectral Amplitude (NSA). These linear simulations are extended to second-order in a perturbation expansion in the frequency domain by utilizing a Fast Fourier Transform (FFT). The nonlinear interaction matrix for waves in shallow-, intermediate-, and deep-water is also investigated. In shallow water, the nonlinear interaction matrix is not as well-behaved as it is in intermediate- and deep-water. The nonlinear interaction matrix is symmetrical with respect to its frequency indices. The value of this nonlinear interaction matrix may, therefore, be calculated only from two octants in the w[subscript m]-w[subscript n] in plane. Water particle kinematics are computed from the simulated sea surface by three different Transfer Functions; viz., (1) Linear Frequency Domain (LFD), (2) Hybrid Frequency Domain (HFD), (3) Ncnlinear Frequency Domain (NFD). Wave pressure forces on a circular cylindrical pile are computed at approximately the mid-depth location in the time domain by the Morrison equation using the Dean and Aagaard coefficients. The statistics of these wave pressure forces are derived by the moment generating function approach by assuming that the initial sea surfaces are linear and Gaussian. The statistics of these simulated sea surfaces and wave pressure forces are compared with those recorded during Hurricane Carla (1961) in the Gulf of Mexico. In the sea surface simulation, the NSA method gives better agreement with the statistics from the measured sea surfaces than the DSA method does. However, there is no conclusion that can be drawn out the wave forces which are simulated from only one record (WPII No. 6887). / Graduation date: 1981

Internal gravity waves transport energy and momentum in both the atmosphere and the ocean. This physical process occurs at such small length scales that it is not captured by coarse resolution numerical models of weather and climate. A series of experiments is presented that model the generation of non-hydrostatic internal gravity waves by intrusions and by the forcing of wind driven turbulent eddies in the surface mixed layer of the ocean. In a first set of experiments, gravity currents intrude into a uniformly stratified ambient fluid and the internal waves that are launched are examined with a finite-volume, full-depth, lock-release setup. In a second set of experiments, isolated rough topography is towed through stratified fluid and the interaction between the turbulent wake and internal waves is investigated. In a third set of experiments, a turbulent shear layer is forced by a conveyor belt affixed with flat plates near the surface of a stratified fluid and downward propagating internal waves are generated. The turbulence in the shear layer is characterized using particle image velocimetry to measure the kinetic energy as well as length and time scales. The internal waves are measured using synthetic schlieren to determine the amplitudes, frequencies, and the energy of the generated waves. Finally, numerical simulations are used to validate and extend the results of laboratory experiments. The thesis will address the question of what fraction of the turbulent kinetic energy of a shear turbulent mixed layer is radiated away by internal waves. Implications for internal waves propagating into the ocean are discussed.