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dc.contributor.authorBrazhnikov, Dmitry
dc.date.accessioned2021-11-27T23:49:37Z
dc.date.available2021-11-27T23:49:37Z
dc.date.issued2021-05
dc.identifier.urihttp://hdl.handle.net/11122/12540
dc.descriptionThesis (Ph.D.) University of Alaska Fairbanks, 2021en_US
dc.description.abstractSurface tides, when obstructed by bottom relief, give rise to periodic oscillations within the stratified oceanic interior. Such transformation of the depth independent (barotropic) tide into internally propagating (baroclinic) waves comprises 1/3 of the global energy losses from the surface tide. Internal waves of tidal period known as internal tides tend to have low vertical shear and hence are very stable and long lived. They have been observed to propagate essentially unchanged across ocean basins. Details of the internal tide wave life-cycle are not well known, yet turbulent dissipation powered by the slow decay of these waves is one of the key processes shaping deep ocean water properties. The Tasman Sea stands out as a natural laboratory to investigate the internal tide life cycle. In this dissertation, the generation and propagation of internal tides were examined by means of realistic simulations of ocean circulation under varying conditions, and were compared to observations obtained during the Tasman Tidal Dissipation Experiment (TTIDE). The simulations reveal that the barotropic-to-baroclinic conversion is intensified at the Macquarie Ridge near New Zealand by coupling with secondary, nonlocally produced internal tides. Because of this complexity, regionally varying hydrographic conditions drive remarkable temporal and spatial variability of internal tide generation. The internal tides that are created at the ridge constructively superpose into a spatially confined, beam-like feature (Tasman beam) that radiates across the Tasman Sea over 1000 kilometers from its generation region and reaches the Tasman shelf. The beam is described well at first order by simple plane wave propagation theory, but also exhibits non-plane wave characteristics associated with diffraction. Additional intricacy arises from development of a standing wave, the result of the beam's reflection near Tasmania. Temporal changes include hydrography-induced refraction and strong perturbations from interactions with eddies. It is concluded that in-situ mooring measurements and ship surveys of internal tides exhibit a great deal of apparent spatial and temporal variability that can be difficult to interpret. This variability can largely be eliminated in the analysis of numerical models which allow the underlying wave field energy life cycle to be quantified.en_US
dc.description.tableofcontentsChapter 1: Introduction -- Chapter 2: Variable internal-tide generation at the Macquarie Ridge -- Chapter 3: Structure and temporal changes of an internal tidal beam in the Tasman Sea -- Chapter 4: Tasman Sea internal tide variability deduced from satellite altimeter, in-situ measurements and numerical simulations -- Chapter 5: General conclusion -- References -- Appendix.en_US
dc.language.isoen_USen_US
dc.subjectTidesen_US
dc.subjectTasman Seaen_US
dc.subjectInternal wavesen_US
dc.subjectLuzon Straiten_US
dc.subject.otherDoctor of Philosophy in Oceanographyen_US
dc.titleInvestigation of variability of internal tides in the Tasman Seaen_US
dc.typeThesisen_US
dc.type.degreephden_US
dc.identifier.departmentDepartment of Oceanographyen_US
dc.contributor.chairSimmons, Harper
dc.contributor.committeeKowalik, Zygmunt
dc.contributor.committeeJohnson, Mark
dc.contributor.committeeMarchenko, Alexey
dc.contributor.committeeHorrillo, Juan J.
refterms.dateFOA2021-11-27T23:49:37Z


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