Shallow Water Variability and its Manifestation in the Interference Pattern of Sound Fields

Петников, В. Г.; Kuz’kin, V. M.

doi:10.1063/1.1486282

Cited by 12 publications

(6 citation statements)

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“…The frequency shift caused by hydrodynamic variability including internal waves has been discussed earlier. [27][28][29][30] In other waveguide conditions, the parameters ␤ and ␥ in Eq. ͑15͒ have different values 12 for a different group of modes.…”

Section: ͑11͒mentioning

confidence: 99%

Robust time reversal focusing in the ocean

Kim

Kuperman

Hodgkiss

et al. 2003

The Journal of the Acoustical Society of America

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Recent time-reversal experiments with high-frequency transmissions (3.5 kHz) show that stable focusing is severely limited by the time-dependent ocean environments. The vertical focal structure displays dynamic variations associated with focal splitting and remerging resulting in large changes in focal intensity. Numerical simulations verify that the intensity variation is linked to the focal shift induced by phase changes in acoustic waves resulting from sound speed fluctuations due to internal waves. A relationship between focal range shift, frequency shift, or channel depth changes is illustrated using waveguide-invariant theory. Based on the analysis of experimental data and numerical simulations, methods for robust time-reversal focusing are developed to extend the period of stable focusing.

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Section: ͑11͒mentioning

confidence: 99%

Robust time reversal focusing in the ocean

Kim

Kuperman

Hodgkiss

et al. 2003

The Journal of the Acoustical Society of America

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“…The black striations in the broad-band sound intensity distribution are the transmission loss valleys (the minima of a group transmission loss curves), which are important characteristics of broadband sound propagation, that are already used in oceanographic tomography [23]. In this paper, the multi-scale line filter is used to measure black linearity of the interference structure for sediment characterization.…”

Section: The Multi-line Filter For Striation Processingmentioning

confidence: 98%

“…Due to the signal processing limitations, the interference structure properties (here referring to the striation slope and position) are not fully exploited for underwater acoustic applications. As demonstrated in former research [23], for given source, receiver depths, receiver range, the striation position (frequency axis) is determined by environment characteristics. To extract the striation position from the interference structure, a multi-line filter is introduced in next section.…”

Section: Sound Fieldmentioning

confidence: 99%

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Acoustic striation processing for ocean bottom characterization

Ren

Hermand

2011

OCEANS 2011 IEEE - Spain

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Broad-band sound field excited by a moving source usually exhibit striations, whose structures are characterized by the propagation medium. Such relationship has been explored for underwater inverse problems, including sediment geoacoustic characterization, source localization and target recognition. The primary step for these applications is feature extraction by interference structure processing. Image processing methods based on the Radon transform, Hough transform and twodimensional fast Fourier transform (FFT) have been used to process the interference structure to estimate the overall slope of the striations. These transforms do not allow extracting local properties of the striation pattern, e.g., the striation positions, which are also closely related to environment properties. In this paper, a multi-scale line filter based on the image Hessian matrix eigenvalues analysis is introduced and applied in searching for geometrical structures that can be regarded as a line. The location and slope of specific striation can be easily estimated from the filtered image for further applications. The possibility of using a set of striation positions for the geoacoustic characterization of a layered ocean bottom is discussed in this paper.

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“…Effects of time-and range-varying waveguide parameters on the striation patterns have also been studied. [2][3][4][5][6] Weston et al 2 observed a change in the frequency-time interference patterns of broadband ͑4.1-4.5 kHz͒ signals that could be explained by the dependency of mode parameters on water depth that changed through the tidal cycle. They derived a simple formula for the slope of the interference patterns by using the expression for the modal interaction distance, and showed that measured slopes of interference patterns agree well with the theoretical predictions.…”

Section: Introductionmentioning

confidence: 99%

Acoustic monitoring of the tide height and slope-water intrusion at the New Jersey Shelf in winter conditions

Turgut

Orr

Pasewark

2007

The Journal of the Acoustical Society of America

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Waveguide invariant theory is used to describe the frequency shifts of constant acoustic intensity level curves in broadband signal spectrograms measured at the New Jersey Shelf during the winter of 2003. The broadband signals (270-330 Hz) were transmitted from a fixed source and received at three fixed receivers, located at 10, 20, and 30 km range along a cross-shelf propagation track. The constant acoustic intensity level curves of the received signals indicate regular frequency shifts that can be well predicted by the change in water depth observed through tens of tidal cycles. A second pattern of frequency shifts is observed at only 30 km range where significant variability of slope-water intrusion was measured. An excellent agreement between observed frequency shifts of the constant acoustic intensity levels and those predicted by the change in tide height and slope water elevations suggests the capability of long-term acoustic monitoring of tide and slope water intrusions in winter conditions.

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Shallow Water Variability and its Manifestation in the Interference Pattern of Sound Fields

Cited by 12 publications

References 0 publications

Robust time reversal focusing in the ocean

Robust time reversal focusing in the ocean

Acoustic striation processing for ocean bottom characterization

Acoustic monitoring of the tide height and slope-water intrusion at the New Jersey Shelf in winter conditions

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