Spatial observations of low-frequency acoustic propagation near isolated seamounts using an autonomous surface vehicle.

Abstract

This work demonstrates the feasibility of using autonomous surface vehicles equipped with a shallow towed acoustic module (TAM) to survey the spatial variability of low-frequency acoustic propagation across complex bathymetry, such as the Atlantis II seamounts in the Northwest Atlantic. The abrupt seamount topography is found to significantly influence the TAM's recordings of chirp transmissions (500-600 Hz band) from a bottom-moored source ∼30 km from the seamounts by notably causing blockage of in-plane propagation paths and complex reverberation arrivals displaying three-dimensional effects, as confirmed by synthetic aperture beamforming. Ray tracing simulations are compared to these observations based on a data-assimilated ocean model.