Passive acoustic measurement of flow velocity in the Straits of Florida

Godin, Oleg A.; Brown, Michael G.; Zabotin, N. A.; Zabotina, Liudmila; Williams, Neil J.

doi:10.1186/s40562-014-0016-6

Cited by 30 publications

(16 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We apply the three-step signal processing technique to the ambient noise recorded by two near-bottom hydrophones in 100 meter-deep water in the Straits of Florida [17,18].…”

Section: Ocean Acoustics Hydroacousticsmentioning

confidence: 99%

“…Sound attenuation in the bottom is α b = 0.3 dB/λ, where λ is the wavelength. The waveguide parameters and the geometry of the problem were chosen to approximate those encountered in an experiment in the Straits of Florida [17,18]. The spectrum of the radiated signal is assumed to be flat in the frequency band that is considered.…”

Section: Numerical Simulations Of a Single-element Trmmentioning

confidence: 99%

“…Furthermore, the simulations do not account for the many uncertainties in the environmental parameters and the problem geometry that are present in field experiments. To investigate the feasibility of time reversal of NCCFs of acoustic noise in the ocean, we use the data obtained in the noise interferometry experiment in the Straits of Florida [17,18]. In this experiment, ambient noise on the continental shelf in the Florida Straits was continuously recorded for 6 days by three autonomous systems 1, 2, and 3.…”

Section: Numerical Simulations Of a Single-element Trmmentioning

confidence: 99%

“…The seafloor slope perpendicular to the paths between the instruments was of the order of 10 -2 . During the experiment, the temperature variations with depth and gradients in the speed of sound were rather weak, with the speed of sound c = 1537.4 ± 2.4 m/s throughout the water column [17,18]. During the experiment, tides with a total range of approximately 1 m were recorded by a tide gauge.…”

Section: Numerical Simulations Of a Single-element Trmmentioning

confidence: 99%

See 3 more Smart Citations

Application of time reversal to passive acoustic remote sensing of the ocean

et al. 2017

View full text Add to dashboard Cite

Application of TimeAbstract⎯This paper investigates a novel approach to processing records of ambient noise in the ocean that are measured concurrently in spatially separated locations. The approach is a synthesis of two well-known phase-coherent signal processing techniques. At the first stage of processing, an approximation to the transient acoustic Green function is found by the method of noise interferometry. At the second stage, the approximate Green function is time reversed and back propagated from the location of one of the receivers, thereby producing a focus in the vicinity of the other receiver. Unlike the earlier work, measurements at just two points (rather than vertical array measurements) are used when the sound-propagation range is large compared to the ocean depth. The requirement for optimal focusing of the back-propagated field is shown to lead to extraction of estimates of the unknown physical parameters of the waveguide and, hence, to passive acoustic remote sensing of the ocean.Keywords: ocean acoustics, noise interferometry, time reversal DOI: 10.1134/S1063771017020038 INTRODUCTION This paper reports an investigation of a novel approach to solving inverse problems, which is based on synthesis of the noise interferometry and the timereversal technique. Roux and Kuperman [1] were the first to consider such a signal-processing technique but without application to inverse problems. We show that the combined use of the noise interferometry and time-reversal techniques allows one to use concurrent records of ambient noise at a few locations for passive acoustic remote sensing of the ocean.The proposed approach is conceptually simple and consists of three steps. At the first signal processing step, the cross-correlation function (NCCF) С AB (t) is computed from concurrent measurements of ambient noise of the ocean at locations A and B. Here, t is the time lag of the signal at B relative to the signal at A. For

show abstract

“…We apply the three-step signal processing technique to the ambient noise recorded by two near-bottom hydrophones in 100 meter-deep water in the Straits of Florida [17,18].…”

Section: Ocean Acoustics Hydroacousticsmentioning

confidence: 99%

Section: Numerical Simulations Of a Single-element Trmmentioning

confidence: 99%

Section: Numerical Simulations Of a Single-element Trmmentioning

confidence: 99%

Section: Numerical Simulations Of a Single-element Trmmentioning

confidence: 99%

See 2 more Smart Citations

Application of time reversal to passive acoustic remote sensing of the ocean

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Cross-correlation functions of pressure fluctuations in the ocean have been investigated in the 0.5-30 mHz band, where the correlations characterize deep-water infragravity waves and their sources (Webb 1986;Godin et al 2014b), and at acoustic frequencies above 1 Hz, where geoacoustic parameters of the seafloor (Brown et al 2014), spatial (Godin et al 2010) and temporal (Woolfe et al 2015) variations of the sound speed in water and ocean current velocity (Godin et al 2014a) have been retrieved from noise cross-correlations.…”

Section: Introductionmentioning

confidence: 99%

Long-range correlations of microseism-band pressure fluctuations in the ocean

Ball

Godin

Evers

et al. 2017

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

We investigate the spatial coherence of underwater infrasonic noise using a yearlong time series measured by hydrophones moored off Ascension Island. Qualitative agreement with observed cross-correlations is achieved using a simple range-dependent model, constrained by earlier, active tomographic studies in the area. In particular, the model correctly predicts the existence of two weakly dispersive normal modes in the microseism frequency range, with the group speed of one of the normal modes being smaller than the sound speed in water. The agreement justifies our interpretation of the peaks of the measured cross-correlation function of ambient noise as modal arrivals, with dispersion that is sensitive to crustal velocity structure. Our observations are consistent with Scholte to Moho head wave coupled propagation, with double mode conversion occurring due to the bathymetric variations between receivers. We thus demonstrate the feasibility of interrogating crustal properties using noise interferometry of moored hydrophone data at ranges in excess of 120 km.

show abstract