Influence of impulsive sources on the soundscape of under-ice Arctic marine mammals

Abstract

The Arctic Ocean exemplifies the danger in using sound propagation and interaction models without a clear understanding of the physics of the problem or weaknesses inherent in these models. The zone-of-influence for under-ice marine mammals should be expected to differ significantly from that of open-sea organisms. However, increasing the effective sound attenuation, to empirically account for sound interactions with keel drafts, may lead to grossly erroneous conclusions from predictive and forensic studies. Ice elasticity and ridges combine to increase water/ice low-frequency sound penetration enabling long-distance transmission along this liquid-solid interface in the form of an evanescent wave. Consequently, sound pressure and exposure levels near the canopy are significantly higher even when the acoustic wavelength is several times longer than the ice thickness. Therefore, these physical mechanisms should also be taken into account in Arctic environmental impact assessment calculations. For example, i...