Modeling acoustic propagation in an ice-covered environment using a hybrid finite element-ray theory approach

Although models of acoustic propagation in an ice-covered environment have been calculated using only finite elements, ray theory models can cover longer distances and higher frequency ranges much more efficiently. In this study, a hybrid approach is taken by calculating the reflection coefficient of the ice using finite elements over a range of frequencies and angles. These values are then inserted into a ray-theory model. Using this model, a study of the sensitivity of common approximations of the ice cover on acoustic propagation is conducted. For example, the ice can be described simply as a pressure release surface or much more complexly as an elastic body with range and depth geo-acoustic property variations. The hybrid finite element-ray theory model will be verified numerically by comparing it to a full finite element propagation model for appropriate ranges and frequencies. [Work sponsored by ONR, Ocean Acoustics.]