Effective ice model for under-ice propagation using the fluid-fluid parabolic equation

Abstract

With recent climate change measurements, interest in acoustic propagation in the Arctic Ocean is being renewed. An approach is presented to permit efficient computation of the waterborne acoustic field in the presence of sea ice. The range-dependent wide-angle parabolic equation (PE) is used to model the acoustic field with a lower-density layer (ice) placed above the ocean and seafloor. The ice layer is characterized by its thickness, compressional speed, density, and attenuation. Acoustic loss due to sea ice is primarily driven by conversion to shear waves, and in this model the effect will be approximated by volume attenuation within the ice layer. Rough interface scattering at the air-ice and ice-water interfaces will be handled by generating range-dependent realizations from a data-derived ice thickness model. An inversion for ice parameters is conducted by matching the multiple frequency Transmission Loss (TL) measurements of Diachok(Diachok, 1976). The predicted frequency dependence of propagation (TL) and impulse responses is presented. © 2013 Acoustical Society of America.