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.
College and Department
Ira A. Fulton College of Engineering and Technology; Mechanical Engineering
BYU ScholarsArchive Citation
Hillyard, Benjamin Lee, "Investigation of Internal Wave Spectra Due to Observed Interactions" (2012). All Theses and Dissertations. 3316.
internal waves, group velocity, dissipation