Location
MC 6460
Candidate
Chichi Zhou | Applied Mathematics, University of Waterloo
Title
The Influence of Wind on Internal Solitary Waves
Abstract
Internal solitary waves (ISWs) are a type of nonlinear internal wave that can propagate over long distances while maintaining their non-sinusoidal form. Their nonlinear nature makes them sensitive to changes in background conditions, such as stratification and shear currents. Commonly observed in the coastal ocean, ISWs are susceptible to the complexity of coastal ocean environments, where they may become unstable and undergo a series of evolution stages and instabilities. Wind, as an important atmospheric forcing, is widely known to induce changes in the upper ocean and therefore has the potential to affect the propagation of ISWs. However, this air-sea coupled effect has not been fully investigated. This study therefore aims to explore the effect of wind on ISW propagation.
In this thesis, we use the MITgcm model equipped with the K-Profile Parameterization (KPP) scheme to study internal solitary waves affected by strong wind. Idealized background conditions are applied to isolate wind-induced effects on the wave field. We begin by performing a series of sensitivity tests to determine the optimal numerical parameters. Numerical simulations under various wind conditions are then conducted to explore how wind direction, strength, and temporal variability in wind stress affect the propagation of internal solitary waves. The analysis focuses on wave characteristics, including amplitude, propagation speed, and the development of instabilities during wave evolution. The effects of wind on the flow field can be summarized as enhanced mixing and the induction of near-surface shear currents. The DJL equation is also introduced to examine the separate effects of these two factors in cases where numerical solutions can be obtained.