Three-dimensional acoustic propagation effects induced by the sea ice canopy.

ABSTRACT

This work examines three-dimensional (3D) propagation caused by interaction with the sea ice canopy using an approximate normal mode/parabolic equation hybrid model. The effects of horizontal refraction are assessed through comparison of two-dimensional (2D) and 3D solutions for the modal amplitudes and depth-averaged transmission loss. The following 3D effects are described diffraction of sound into shadow zones behind ice keels, horizontal defocusing of sound behind ice keels, and horizontal focusing of sound that has propagated between ice keels. A statistical analysis shows that the 3D solution is characterized by 20% greater variance in the depth-averaged transmission loss than the 2D solution.