Numerical analysis of underwater sound propagation over the Chukchi Sea shelfbreak

Abstract

During the 2015 Canada Basin Acoustic Propagation Experiment (CANAPE) expedition on the southern edge of Canada basin (northern Chukchi Sea shelfbreak), shipboard suspended underwater sound sources were deployed to transmit acoustic signals to hydrophone arrays moored on the deep basin as well as the shallow shelf. In this paper, numerical simulations utilizing the Parabolic Equation method are conducted to provide physical insights into the variability of signals propagating over the shelfbreak and slope and recorded on a vertical array on the Chukchi Sea shelf. The numerical models simulate sound propagating over the slope via the Pacific Halocline duct, which is a water-borne vertical sound duct formed between the layers of Pacific summer water and Atlantic water. The source to receiver distance is about 130 km, and realistic variability is introduced in the numerical models. The previous studies reported in the literature have concluded that the shelfbreak circulation, specifically upwelling, and the sub-mesoscale eddies spun off the shelfbreak jet are the two major causes of the temporal and spatial variability of the Pacific Summer Water Layer over the slope in the region. The numerical simulation study also emphasize on the scattering and attenuation effects caused by ice cover and roughness. A preliminary data-model comparison is made and discussed in this paper. [Work supported by the Office of Naval Research.]