Fundamentals of Ocean Acoustics

Jensen, Finn B.; Kuperman, W. A.; Porter, Michael B.; Schmidt, Henrik

doi:10.1007/978-1-4419-8678-8_1

Cited by 97 publications

(149 citation statements)

References 28 publications

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“…This offset from 0 s identifies that the single velocity model is too simple; the propagation velocity to H08S is too low. Therefore, a normal mode propagation model is used to estimate the velocity to H08S and H01W from an average source location 51 ı S, 105 ı E [Jensen et al, 2000;Green et al, 2013], where the axis depth is about 200 m. The resulting velocities are 1485 and 1480 m/s for H08S and H01W, respectively. The corresponding t distribution now has its median at -7 s, with a standard deviation of 17 s ( Figure S1), which will be used as t threshold.…”

Section: Localizing the Sourcesmentioning

confidence: 99%

“…Acoustic waves travel efficiently through the SOFAR (Sound Fixing and Ranging) channel, with an average depth of the axis at between 1 and 2 km water depth [Jensen et al, 2000], enabling the detection of low energy events over long ranges. For example, the IMS triplet hydrophone arrays deployed in the SOFAR channel have detected signals from explosions of less than 40 kg Trinitrotoluene (TNT) at ranges up to 16,000 km [Prior et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

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Remote hydroacoustic sensing of large icebergs in the southern Indian Ocean: Implications for iceberg monitoring

Evers

Green

Young

et al. 2013

Geophysical Research Letters

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[1] Hydroacoustic signals generated by drifting icebergs that crack, disintegrate, and collide were identified on two hydrophone arrays in the Indian Ocean. These hydrophone arrays are deployed in the Sound Fixing and Ranging channel, enabling the detection of small sources over ranges of several thousand kilometers due to the low attenuation. Source locations estimated from the signal bearings at the arrays are used to monitor two very large icebergs, C20 and B17B. Spatial and temporal correlation of the location estimates with satellite observations confirm that the icebergs can be hydroacoustically resolved. Hydroacoustic generation rates at both C20 and B17B are highest at times of observed breakup. For C20, which underwent continuous breakup, clusters of events to the southeast of the main iceberg show that hydroacoustic observations can identify trails of icebergs that calved from the main berg whose dimensions are less than that easily resolved by moderate resolution satellite monitoring.

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Section: Localizing the Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Remote hydroacoustic sensing of large icebergs in the southern Indian Ocean: Implications for iceberg monitoring

Evers

Green

Young

et al. 2013

Geophysical Research Letters

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“…Equation 2.1 shows the speed of sound as a function of temperature (T ( • C)), depth (z (m)), and salinity (S (ppt)) [1]. …”

Section: Classic Arctic Acoustic Environmentmentioning

confidence: 99%

“…Underwater acoustic wave propagation is governed by the wave equation which can be linearly approximated as shown below. The following derivations are standard reference material and included to establish notation [1], [6].…”

Section: Underwater Acousticsmentioning

confidence: 99%

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Low frequency active sonar performance in the Arctic Beaufort Lens

Carper¹

2017

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A newly discovered double ducted acoustic environment present throughout much of the Beaufort Sea in the Arctic has a major effect on active acoustic transmissions. This work performs an in depth analysis of how the lower duct impacts the propagation of various active signals used commonly for acoustic communications or active sonar. First, this thesis performs a thorough modal analysis of the effect of the double ducted environment on long range propagation of a 300 Hz and 3500 Hz pulse. Signal excess is determined for the two different source pulses to quantify the effect of the lower duct on noise and SNR. Finally, channel capacity is calculated for the two frequency bands to evaluate operational impacts of the lower duct on acoustic communication systems in the Arctic.

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On infrasound generated by wind farms and its propagation in low‐altitude tropospheric waveguides

et al. 2015

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Infrasound from a 60‐turbine wind farm was found to propagate to distances up to 90 km under nighttime atmospheric conditions. Four infrasound sensor arrays were deployed in central New Mexico in February 2014; three of these arrays captured infrasound from a large wind farm. The arrays were in a linear configuration oriented southeast with 13, 54, 90, and 126 km radial distances and azimuths of 166°, 119°, 113°, and 111° from the 60 1.6 MW turbine Red Mesa Wind Farm, Laguna Pueblo, New Mexico, USA. Peaks at a fundamental frequency slightly below 0.9 Hz and its harmonics characterize the spectrum of the detected infrasound. The generation of this signal is linked to the interaction of the blades, flow gradients, and the supporting tower. The production of wind‐farm sound, its propagation, and detection at long distances can be related to the characteristics of the atmospheric boundary layer. First, under stable conditions, mostly occurring at night, winds are highly stratified, which enhances the production of thickness sound and the modulation of other higher‐frequency wind turbine sounds. Second, nocturnal atmospheric conditions can create low‐altitude waveguides (with altitudes on the order of hundreds of meters) allowing long‐distance propagation. Third, night and early morning hours are characterized by reduced background atmospheric noise that enhances signal detectability. This work describes the characteristics of the infrasound from a quasi‐continuous source with the potential for long‐range propagation that could be used to monitor the lower part of the atmospheric boundary layer.

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Fundamentals of Ocean Acoustics

Cited by 97 publications

References 28 publications

Remote hydroacoustic sensing of large icebergs in the southern Indian Ocean: Implications for iceberg monitoring

Remote hydroacoustic sensing of large icebergs in the southern Indian Ocean: Implications for iceberg monitoring

Low frequency active sonar performance in the Arctic Beaufort Lens

On infrasound generated by wind farms and its propagation in low‐altitude tropospheric waveguides

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