Use of Linear Receiving Arrays for Observing Horizontal Refraction of Low-Frequency Sound in Shallow Water with a Strongly Inhomogeneous Waterlike Bottom

• Published in: Acoustical physics Vol. 68; no. 4; pp. 357 - 364
• Main Authors: Lunkov, A. A., Petnikov, V. G., Sidorov, D. D.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.08.2022; Springer; Springer Nature B.V
• Subjects: Acoustic waves; Acoustics; Arrays; Beamforming; Numerical analysis; Ocean Acoustics. Hydroacoustics; Physics; Physics and Astronomy; Refraction; Sediments; Seismic surveys; Shallow water; Sound propagation; Spatial distribution; Transmission loss; Wave propagation; Waveguides; shallow-water acoustics; marine sediment acoustics; sound propagation on the Arctic shelf
• ISSN: 1063-7710; 1562-6865
• DOI: 10.1134/S1063771022040066

Numerical simulation is applied to study the features of a low-frequency (55 and 137 Hz) acoustic field and its recording by linear horizontal and vertical arrays in a shallow-water waveguide with a depth of ≈30 m and an inhomogeneous bottom. The area where the sound speed in the bottom is close that in water is considered. For calculations, we used the spatial distribution of the sound speed in the Kara Sea bottom sediments, obtained during engineering seismic survey, as well as test drilling data. It is shown that an inhomogeneous bottom not only affects the depth-averaged loss during sound propagation, which can be detected by a vertical array, but also leads to horizontal refraction of acoustic waves, which manifests itself during beamforming at an extended horizontal array. The maximum effects are observed for a low frequency (55 Hz): the decrease in transmission losses reaches 5 dB, and the bias in the maximum response of the array is 3.4°.