Climate Seminar - Boury

Mon, Oct 25, 2021, 4:00 pm
Location: 
Zoom - see link from Allison Hogikyan
Audience: 
Open to all Princeton students, staff, and faculty.
Speaker(s): 
Sponsor(s): 
AOS
Geosciences

Abstract:

Inertia-gravity waves contribute to the worldwide transport of energy and momentum in the oceans and play a crucial role in stratified mixing, transferring energy from scale to scale through non-linear processes such as super-harmonic generation (SHG) or triadic resonant instability (TRI). Recently, these waves have drawn a lot of attention due to their potential role in climate models and in the mixing of highly stratified oceans, notably the Arctic Ocean. Due to increasing sea ice melting in the last decades, the surface of the Arctic Ocean is now more exposed throughout the year to atmospheric storms and winds, whose local forcing of the pycnocline may generate energetic internal waves. The strongly stratified layers of the Arctic Ocean can be more easily disturbed by atmospheric events and, in return, the modified dynamics of energy transport plays a crucial role in regional climate changes. A better understanding of how storms energy can be transferred to the ocean --and how it can propagate through it-- is thus of primary importance.

While the predominant internal wave models are based on two-dimensional Cartesian plane waves, they are not adapted here as the storm-excited waves follow a more complex, three-dimensional, geometry. Based on these considerations, I will discuss how internal wave propagation in stratified and rotating media is impacted by changing the geometry from pure Cartesian plane waves to axisymmetric radially decreasing waves. This provides new perspectives on a wide range of dynamics, such as modes and wave resonators, transmission through buoyancy interfaces and tunneling effect, super-harmonic generation (SHG) and triadic resonant instability (TRI), and wave attractors. The theoretical framework derived for these waves is validated by laboratory experiments, through the use of a storm-like axisymmetric wave generator creating inertia-gravity waves, in confined and unconfined cylindrical geometries. Applications to in-situ measurements are also proposed with comparisons to internal waves in real world stratifications.

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