Theory and analysis of acoustic-gravity waves in a free-surface compressible and stratified ocean: Impact of the bottom-boundary condition

Abstract

Auclair et al. (2021) analyzed the propagation of acoustic-gravity waves (AGWaves) in the ocean and showed that AGWaves dispersion can be described based on the inner and boundary dispersion relations. A major limitation to their two-dispersion-relation model is the assumption of a rigid bottom boundary since acoustic waves can cross the ocean bottom and propagate in the sediment. An extension of their AGWaves-dispersion model is consequently proposed toward a more realistic two-layers fluid model. This improvement enables the evaluation of the perspectives opened by the new generation of compressible ocean models for ocean-acoustics applications. The acoustic regimes in this resulting model are shown to be in agreement with underwater acoustics literature. In addition, the free-surface boundary condition is in turn compared to the pressure release boundary condition to establish a bridge with classical acoustic dispersion models.