Analysis of acoustic propagation characteristics of the low salinity lens outside the Pearl River Estuary

QU Ke; MO long-ying; LI Zhang-long

doi:10.3969/j.issn.1001-909X.2019.01.003

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Journal of Marine Sciences ›› 2019, Vol. 37 ›› Issue (1) : 15-20. DOI: 10.3969/j.issn.1001-909X.2019.01.003

Analysis of acoustic propagation characteristics of the low salinity lens outside the Pearl River Estuary

QU Ke, MO long-ying, LI Zhang-long

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Abstract

Low salinity lens is a common mesoscale phenomenon in the continental shelf outside the Pearl River Estuary, and its appearance will affect the underwater acoustic waveguide. The structure characteristics of low salinity lenses were analyzed based on the CTD profiles in the northern shelf of the South China Sea. Based on the normal mode and ray model, the two-dimensional waveguide environment was established, the characteristics of sound transmission in the low salinity lenses environment were studied under different sound source conditions. The results show that the low salinity lens will become the acoustic channel in the upper layer of sea water, and the transmission loss at 15 km is about 15 dB less than that without low salinity lens. Although the channel thickness of low salinity lens is usually smaller than surface acoustic channel, the large salinity gradient can effectively trap energy in the acoustic channel. When the sound source whose frequency is higher than the cut-off frequency is placed in a low-salt lens, the acoustic channel can help the long-distance propagation of sound.

Key words

Pearl River Estuary / low salinity lens / transmission loss / acoustic channel

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QU Ke, MO long-ying, LI Zhang-long. Analysis of acoustic propagation characteristics of the low salinity lens outside the Pearl River Estuary[J]. Journal of Marine Sciences. 2019, 37(1): 15-20 https://doi.org/10.3969/j.issn.1001-909X.2019.01.003

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