UC San Diego

Internal waves play a fundamental role in ocean mixing and the global overturning circulation, yet their energy pathways remain poorly quantified in energetic high-latitude regions. This dissertation investigates internal wave energy transport in the Southern Ocean and coherent internal tide detection in the Southern Ocean and the high-latitude North Atlantic, combining high-resolution ocean modeling and satellite altimetry.The first part quantifies the meridional redistribution of internal wave energy in the Southern Ocean using the 1/48° global MITgcm LLC4320 simulation. By decomposing fluxes into tidal, near-inertial, and continuum bands, I demonstrate that the semidiurnal tide is the dominant component of meridional energy transport, driving a net poleward flux of O(10) GW that accounts for over 80% of the total. The strong flux convergence near Antarctica implies diapycnal diffusivities consistent with observed background interior mixing rates in the Southern Ocean, suggesting that poleward-propagating internal tides are a meaningful energy source for near-Antarctic mixing. In contrast, despite intense wind forcing, only 1–4% of the near-inertial wind power input is exported from the generation sites, suggesting that wind energy is dissipated predominantly locally.The second part maps coherent mode-1 M2 internal tides across the Southern Ocean by applying two-dimensional plane-wave fitting to SWOT Cal/Val observations. SWOT’s wide-swath geometry and short aliasing period enable detections in strongly eddying regions where conventional altimetry is limited, including Drake Passage and the Southwest Indian Ridge, revealing beam attenuation across Antarctic Circumpolar Current fronts and phase curvature consistent with mesoscale refraction. I then extend the mapping to the Iceland region using 21 months of SWOT science orbit data, producing the first satellite-derived maps of mode-1 M2 internal tides in this high-latitude region. Coherent propagation is resolved in the quiescent Norwegian Sea but largely obscured in eddy-rich basins to the south. Comparison with the Cal/Val orbit reveals coherent tidal signals in the Iceland Basin that are not recovered in the science orbit results. To support these analyses, I develop an open-source Python package for plane-wave-based internal tide extraction from sea surface height (SSH) observations with quantified uncertainties.Together, these studies advance understanding of internal wave energy pathways in the high-latitude oceans, demonstrate LLC4320’s and SWOT’s capabilities and limitations, and provide open-source tools for the broader community.