Acoustic observations of internal tides and tidal currents in shallow water

Turgut, Altan; Mignerey, Peter C.; Goldstein, David J.; Schindall, Jeffrey A.

doi:10.1121/1.4792141

Cited by 6 publications

(2 citation statements)

References 6 publications

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“…Figures 9A,B show the zonal (U i ) and meridional (V i ) components of the current velocity measured at 8-m intervals between 17 and 65 m of water depth and their respective mean values (thick black circles). Overall, the water column moves in the same direction (i.e., barotropic) with a semi-diurnal cycle, indicating the dominance of the tidal current in the region (Turgut et al, 2013;Noh et al, 2014;Lozovatsky et al, 2015). The current speed estimated by (Parker, 2007;Hicks, 2013).…”

Section: Correlation Of Snap Rate and Environmental Factorsmentioning

confidence: 90%

Temporal Variability in Acoustic Behavior of Snapping Shrimp in the East China Sea and Its Correlation With Ocean Environments

et al. 2021

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The snapping shrimp sound is known to be a major biological noise source of ocean soundscapes in coastal shallow waters of low and mid-latitudes where sunlight reaches. Several studies have been conducted to understand the activity of snapping shrimp through comparison with surrounding environmental factors. In this paper, we report the analysis of the sound produced by snapping shrimp inhabiting an area where sunlight rarely reaches. The acoustic measurements were taken in May 2015 using two 16-channel vertical line arrays (VLAs) moored at a depth of about 100 m, located ∼100 km southwest of Jeju Island, South Korea, as part of the Shallow-water Acoustic Variability Experiment (SAVEX-15). During the experiment, the underwater soundscape was dominated by the broadband impulsive snapping shrimp noise, which is notable considering that snapping shrimp are commonly observed at very shallow depths of tens of meters or less where sunlight can easily reach. To extract snapping events in the ambient noise data, an envelope correlation combined with an amplitude threshold detection algorithm were applied, and then the sea surface-bounced path was filtered out using a kurtosis value of the waveform to avoid double-counting in snap rate estimates. The analysis of the ambient noise data received for 5 consecutive days indicated that the snap rate fluctuated with a strong one-quarter-diurnal variation between 200 and 1,200 snaps per minute, which is distinguished from the periodicity of the snap rate reported in the euphotic zone. The temporal variation in the snap rate is compared with several environmental factors such as water temperature, tidal level, and current speed. It is found that the snap rate has a significant correlation with the current speed, suggesting that snapping shrimp living in the area with little sunlight might change their snapping behavior in response to changes in current speed.

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Section: Correlation Of Snap Rate and Environmental Factorsmentioning

confidence: 90%

Temporal Variability in Acoustic Behavior of Snapping Shrimp in the East China Sea and Its Correlation With Ocean Environments

et al. 2021

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“…Since a workshop held at the beginning of the 21st century, 5) many researchers have become interested in understanding and applying broadband interferences in an ocean waveguide. [6][7][8][9][10][11] As the second workshop of the same title was held recently in June 2013, 12) it can be said that the interest is still strong. Much of the interest is concerned with shallow water environments.…”

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confidence: 99%

Shift of the interference extrema of low-frequency acoustic propagations near the axis of a deep sound channel

Lee

Yoo

et al. 2015

Jpn. J. Appl. Phys.

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Broadband interference patterns measured from acoustic propagations near the axis of a deep sound channel are interpreted. Analyses using mode theory for the waveguide with bilinear sound speed profiles show that the increase in sound speed without gradient variation shifts the positions of intensity maxima to higher frequencies in a fixed range whereas the increase in the gradient shifts the maxima to lower frequencies. Analytic results imply that the frequency shift of intensity extrema appearing in the measurements could be explained by the increase in the sound speed gradient above the axis of the deep sound channel.

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Passive acoustic monitoring of coastal dynamical oceanographic phenomena using single hydrophone

Kinda

Bonnel

2014

2014 IEEE Sensor Systems for a Changing Ocean (SSCO).

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International audienceDuring long term passive acoustic monitoring in shallow water in Iroise Sea, the time series of the ambient noise recorded with a single hydrophone showed some unusual striations in the time-frequency domain. The changes in the striation slopes are related to the tidal oscillations, which induce a change in the water depth of the waveguide. The observed striations are highly correlated with the tides, and this phenomenon is classically described by a simple scalar γ called the depth-frequency waveguide invariant. However, the observed invariant γobs ≃ -1 differs from the canonical γ = -2 value. A theoretical approach is developed to explain the observed γobs, and particularly its dependence on the bathymetry in a range-dependent environment

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Acoustic observations of internal tides and tidal currents in shallow water

Cited by 6 publications

References 6 publications

Temporal Variability in Acoustic Behavior of Snapping Shrimp in the East China Sea and Its Correlation With Ocean Environments

Temporal Variability in Acoustic Behavior of Snapping Shrimp in the East China Sea and Its Correlation With Ocean Environments

Shift of the interference extrema of low-frequency acoustic propagations near the axis of a deep sound channel

Passive acoustic monitoring of coastal dynamical oceanographic phenomena using single hydrophone

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