DEOS PhD Dissertation Defense: "Waves and Vortices in the Ocean - From Theory to Practice" by Bailey Remy
Department of Estuarine and Ocean Sciences
PhD Dissertation Defense
"Waves and Vortices in the Ocean - From Theory to Practice"
By: Bailey Remy
Advisor:
Dr. Miles Sundermeyer (UMass Dartmouth)
Committee Members:
Dr. Geoffrey Cowles (UMass Dartmouth), Dr. Banafsheh Seyed-Aghazadeh (UMass Dartmouth), and Dr. Marie-Pascale Lelong (NorthWest Research Associates)
Monday May 18, 2026
11:00 AM
SMAST East 101-103
836 S. Rodney French Blvd, New Bedford
and via Zoom
Abstract:
Internal waves (IWs) are ubiquitous in the ocean and contribute significantly to the global ocean energy balance by cascading tidal and wind-driven energy to dissipative scales. Vortical motions (VMs), which exist at scales similar to IWs, carry potential vorticity (PV) and influence ocean circulation, mixing, and climate variability. Distinguishing these motions remains a fundamental challenge, as nonlinear interactions in fully developed flows obscure their individual signatures. This dissertation addresses two aspects of IWs and VMs in the ocean. Chapters 1 and 2 investigated mechanisms of energy exchange between IWs and VMs, and the physical signatures and associated dynamics of reduced stratification regions in the ocean. Chapter 3 examined the use of IW and VM signatures to detect underwater wakes in realistic ocean environments.
Chapter 1 examined energy exchange between IWs and VMs in the ocean, focusing on the contrasting roles of linear and nonlinear flow components in shaping available potential vorticity (APV) fields. In numerical simulations initialized with a Garrett-Munk IW spectrum, energy was rapidly projected onto the linear VM basis by nonlinear triad interactions. Idealized simulations of a single linear IW, a balanced vortex, and an adjusting density anomaly exposed limitations of the linear flow decomposition: Lagrangian particle tracking revealed that linear APV differed from total APV due to nonlinear vortex stretching terms, causing the linear decomposition to overestimate the PV-carrying component of flow. These results suggest that apparent rapid VM generation can sometimes reflect nonlinear artifacts rather than true PV modification.
Chapter 2 examined the prevalence and nature of reduced stratification regions in the ocean relative to IW and VM dynamics. Occupying between ~5% and 25% of the model domain, such regions exhibited distinct morphological and dynamical signatures consistent with linear theory. Regions of reduced stratification that projected onto linear VMs exhibited aspect ratios exceeding the canonical N0/f scaling, and horizontal scales exceeding the local Rossby deformation radius. Regions that projected onto linear IWs more closely follow theoretical wave scaling and propagation characteristics. Lagrangian particle tracking and spectral shear-to-strain ratios further distinguished propagating wave motions from materially conserved vortical motions. Additionally, the generation of VM stratification anomalies was found to be energetically more consistent with prolonged mixing events (time scales longer than a buoyancy period) than intense short-term mixing events. These findings confirm that reduced stratification regions in the ocean can result from both internal wave straining and persistent vortical motions, and that certain interactions between them are consistent with current dynamical understanding of both phenomena.
Building on increased understanding of the relationship between IWs and VMs in the ocean, Chapter 3 explored the generation and evolution of IWs and VMs in the wake of a towed body, and their exploitation for the purposes of wake detection. Numerical simulations initialized using an idealized late wake approximation showed that the vortex street generated by the wake was readily detected via potential enstrophy even amid a strong background IW field. IWs radiated during buoyant collapse of the wake were also readily detected among varying background conditions due to their highly coherent radiation pattern. Wake evolution depended on both nondimensional and dimensionful parameters associated with the wake; vortex evolution time scales varied with Froude number, while wave detectability was primarily influenced by wake diameter modulating signal intensity. Overall, these results suggest that, when carefully considered, both IW and VM signatures of submerged wakes can be readily detected under a wide range of conditions even amid the “noisy” background internal wave field of the ocean.
Join Meeting
https://umassd.zoom.us/j/95380787170
Note: Meeting ID and passcode required- email contact to obtain.
For additional information, please contact Callie Rumbut at c.rumbut@umassd.edu
SMAST East 101-103
: 836 S. Rodney French Boulevard, New Bedford MA 02744
Callie Rumbut
c.rumbut@umassd.edu
https://umassd.zoom.us/j/95380787170