Seafloor noise ensemble from vessel manoeuvre in the central North Sea. (15th January 2020)

• Record Type: Journal Article
• Authors: Li, Jianghui; White, Paul R.; Roche, Ben
• Is Part Of: Ocean engineering. Volume 196(2020)
• Publication Date: 2020-01-15
• Subjects: Underwater acoustics -- Seafloor -- Tide -- Wind -- Shipping noise -- Vessel manoeuvre; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2019.106836
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Anthropogenic noise, e.g., shipping noise, are usually unavoidable and radiate over a certain area, e.g., 10 km depending on the noise source level and acoustic propagation channel, which might affect seabed acoustic engineering as well as species' communication, behaviour, fitness and consequently their survival. Therefore, better understanding of these noise sources allows better prediction of performance of seafloor acoustic research, engineering, and biological environment. Measurements from a hydrophone system mounted on the seafloor in the central North Sea permit comparisons between temporal and spectral seafloor noise as a vessel transits nearby. The measured data indicates that the peak energy in the power spectral density (PSD) of seafloor noise is dominated by that of multiple vessel tonal noise. The tidal level has a strong negative correlation with the seafloor noise variance, and the vessel to hydrophone angle has a modest negative correlation with both the noise variance and kurtosis, particularly within a certain distance (6.6 km at depth 150 m here). As the vessel approaches, the seafloor noise is sensitive to the noise radiated from the vessel manoeuvre dominated at frequencies 400–900 Hz. Further, as the vessel speed increases from 2 knots to 15 knots, the vessel tonal increases the PSD by 10–20 dB at multiple narrow frequency bands (770 and 850 Hz). Results reported here advance the knowledge of seafloor acoustic sensitivity to nearby transit vessels. Highlights: Seafloor noise has been measured as a vessel transits nearby in the central North Sea. Peak energy of seafloor noise is dominated by vessel tonal noise. Strong negative correlation between tidal level and seafloor noise variance. Seafloor noise is sensitive to vessel manoeuvre at frequencies 400–900 Hz.