Midfrequency acoustic propagation and reverberation in a deep ice-covered Arctic ocean

Abstract

A model-based analysis of sound transmission in a deep ice-covered Arctic ocean recorded during the Ice Experiment 2014 is presented. A source of opportunity transmitted mid-frequency (3500 Hz) 5 s duration continuous wave pulses. The source and receiver were omnidirectional, located under ice at a ∼30 m depth at a ∼719 m distance from each other. Recorded acoustic intensity time series showed a clear direct blast signal followed by an about 30 s duration reverberation coda. The model considers several types of arrivals contributing to the received signal at different time intervals. The direct signal, corresponding to a short-range nearly horizontal propagation, is strongly affected by the presence of a weak near-surface (within 50 m depth) acoustic channel. Reverberation coda that follows the direct signal corresponds to medium-range bottom- and ice-bounced arrivals from steep angles which are controlled by reflectivity and scattering strengths of ice and bottom, their physical properties, and acoustical parameters.