Energy and Buoyancy Transport by Inertia-Gravity Waves in Non-Linear Stratifications. Application to the Ocean

• Main Author: Boury, Samuel
• Other Authors: Laboratoire de Physique de l'ENS Lyon (Phys-ENS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Department of Mechanical Engineering Massachusetts Institute of Technology (MIT-MECHE), Massachusetts Institute of Technology (MIT), Université de Lyon, Philippe Odier, Thomas Peacock
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2020
• Subjects: Fluid Mechanics; Internal Waves; Non-Linear Processes; Physical Oceanography; Mécanique des fluides; Ondes internes; Phénomènes non-linéaires; Océanographie Physique; [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Arctic; Arctic Ocean; Arctique*
• Online Access: https://theses.hal.science/tel-02921569; https://theses.hal.science/tel-02921569/document; https://theses.hal.science/tel-02921569/file/BOURY_Samuel_2020LYSEN014_These.pdf

Inertia-gravity waves contribute to the worldwide transport of energy and momentum in the oceans, and theyplay a crucial role in stratified mixing through non-linear processes transferring energy from scales to scalessuch as super-harmonic generation or triadic resonant instability.Of primary relevance are these waves to the Arctic Ocean, and more particularly energy transport by internalwaves created by storms at the surface of the ocean. Due to increasing ice melting in the last decades, thesurface of the Arctic Ocean is more exposed to winds and storms than ever and for a longer durationthroughout the year. The very stratified layers of the ocean can now be disturbed by atmospheric events and,in return, the modified dynamics of energy transport plays a crucial role in climate changes. A betterunderstanding of how storm energy can be transferred to the ocean, and of how it can propagate through, isa very relevant issue.Based on these considerations, this thesis explores the impact of the geometry on internal wave propagationin stratified and rotating media, both in the linear and non-linear theory. Different phenomena such as modes,wave resonator, transmission though buoyancy interface, tunnelling effect, super-harmonic generation andtriadic resonant instability, wave attractors, are discussed. Theory is validated by experiments, through the useof a storm-like axisymmetric wave generator creating inertia-gravity waves in stratified and rotating fluids, inconfined and unconfined cylindrical geometries. Applications to in-situ measurements are also proposed withcomparisons to internal waves in real world stratifications. Les ondes gravito-inertielles contribuent au transport global d’énergie et d’impulsion dans les océans, et elles jouent un rôle crucial dans le mélange stratifié par des processus non-linéaires transférant l'énergie d'une échelle à l'autre, comme la génération de super-harmoniques ou l'instabilité résonante triadique. Ces ondes sont d'une importance capitale pour l'océan Arctique, et plus ...