Theoretical, field and experimental study on internal wave dynamics in rotating stratified basins

摘要

A linear analysis based on modal decomposition of layer-averaged shallow water equations was used to identify the main basin-scale internal waves in rotating, stratified water bodies and to predict the evolution of such internal waves in response to the forcing effect of wind. The analysis was applied both to Lake Villarrica, a stratified, Coriolis affected lake located in Southern Chile, and to an experimental two-layer stratified circular basin mounted on a rotating table. The modal analysis correctly predicts the observed periods of internal waves in Lake Villarrica and identifies the occurrence of a quasi-resonant condition in the lake, generated by the wind period being close to that of the fundamental Kelvin wave. The same situation occurs in the rotating circular basin. In this case the characteristics of the wind can create the excitation of different basin-scale internal waves and resonance under proper conditions. Preliminary experimental observations are used to validate the results of the modal analysis.