Surface Backscattering Strengths Measured over an Extended Range of Frequencies and Grazing Angles

Chapman, R. P.; Scott, H D

doi:10.1121/1.1919274

Cited by 30 publications

(12 citation statements)

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“…Further, to incorporate more eigen-rays with the above classification, as in References [20,27], we extend these notations with a subscript n , i.e. , SS n , SB n , BS n , BB n , to define a ray with a bounce time order n .…”

Section: Stratified Acoustic Model Developmentmentioning

confidence: 99%

A Stratified Acoustic Model Accounting for Phase Shifts for Underwater Acoustic Networks

Wang

Zhang

2013

Sensors

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Accurate acoustic channel models are critical for the study of underwater acoustic networks. Existing models include physics-based models and empirical approximation models. The former enjoy good accuracy, but incur heavy computational load, rendering them impractical in large networks. On the other hand, the latter are computationally inexpensive but inaccurate since they do not account for the complex effects of boundary reflection losses, the multi-path phenomenon and ray bending in the stratified ocean medium. In this paper, we propose a Stratified Acoustic Model (SAM) based on frequency-independent geometrical ray tracing, accounting for each ray's phase shift during the propagation. It is a feasible channel model for large scale underwater acoustic network simulation, allowing us to predict the transmission loss with much lower computational complexity than the traditional physics-based models. The accuracy of the model is validated via comparisons with the experimental measurements in two different oceans. Satisfactory agreements with the measurements and with other computationally intensive classical physics-based models are demonstrated.

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Section: Stratified Acoustic Model Developmentmentioning

confidence: 99%

A Stratified Acoustic Model Accounting for Phase Shifts for Underwater Acoustic Networks

Wang

Zhang

2013

Sensors

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“…Analysis of Reverberation Data Figure 1 shows some typical results obtained from deep-ocean reverberation expeiiments for scattering versus frequency at a fixed grazing angle. Chapman and Scott 1964;Percy, 1970;Brown et al, 1966). To use the data to estimate the horizontal wavenumber spectrum P(qh) as a function of qh, we convert the measured backscatter strength, BS (in decibels), to a scattering ci iss section per unit area,…”

Section: U the Wavenumbep Spectrum For Sound-speed Flucituations In mentioning

confidence: 99%

“…In Fig. 3 we show the inferred values for the spectral exponent p as a function of windspeed for the 12 measurements Chapman and Scott 1964;Percy, 1970;Brown et al, 1966;Jin et. al, 1989).…”

Section: Floogio(•ma)mentioning

confidence: 99%

NCPA Planning, Organization and Research FY 92

Crum¹,

Gilbert²,

Breazeale³

et al. 1994

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“…U(W) is the wind speed dependent at height 10 m, and expressed as (27) D(z, W) is also written as (28) Here, W is the wind speed in m/s, L(W) is called folding depth. Wu [48], and Crawford and Farmer [49] proposed the following two relations, respectively, to calculate the folding depth L(W) When bubble plume is determined, it would be possible to calculate the sound speed in the bubbly water using (30) where:…”

Section: Bubbles Modelingmentioning

confidence: 99%

Low Frequency Sound Scattering from Rough Bubbly Ocean Surface: Small Perturbation Theory Based on the Reformed Helmholtz-Kirchhoff-Fresnel Method

Ghadimi

Bolghasi

Chekab

2015

Journal of Low Frequency Noise, Vibration and Active Control

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Through the use of perturbation theory, Kuo has previously introduced a joint surface roughness/volumetric model in order to characterize bubbly sea surface reverberation based on volumetric wave spectra, surface roughness wave spectrum, and correlation of volumetric wave spectrum and surface roughness wave spectrum. Due to the lack of undetermined volumetric scattered wave number K n , Kuo obtained backscattering strengths using only PiersonMoskwitz wave spectrum. In this paper, the reformed integral equation of authentic Helmholtz-Kirchhoff-Fresnel is discussed in which volumetric scattering is involved. By applying the reformed Helmholtz-Kirchhoff-Fresnel, volumetric scattered acoustic pressure field P n is obtained. Using Helmholtz wave equation and the obtained pressure field P n , the wave number vector of volumetric scattered field K n is calculated, and this used to compute the volumetric wave spectrum and the joint surface roughness/volumetric wave spectrum. The obtained spectra are then used to compute scattering strengths. Comparison of the obtained results against the results of experimental Critical Sea Tests shows good agreement. Finally, a parametric study is conducted to examine the effects of wind speeds, grazing angles, and frequencies on the scattering strengths. Keywords: Small Perturbation Method; Sound Scattering; Helmholtz-KirchhoffFresnel Integral; Bubble Plumes INTRODUCTIONEffects of sea surface on the incident sound have been examined by different acousticians due to its important role on sound propagation and reverberation and wide variety of sound applications in underwater environment. Underwater acoustic communication channels [1][2][3][4][5], sound emission from the submerged and floating objects [6,7], sound scattering of underwater sources from the sea surface [8] are among the most important subjects in underwater acoustics related to sea surface effects. In most of these subjects, it is necessary to provide an appropriate acoustic model in order to entail sea surface effects on the entry sound. Active control and acoustic response of structure and fluid interaction [9,10], attenuation and absorption [11], bubble plumes [12][13][14][15], sound transmission [16][17][18], sound propagation in shallow water [19][20][21] and surface waves [22][23] can be considered as important phenomena in the sea.There are different approaches adopted by investigators in order to examine sound scattering from the sea surface. These approaches can be categorized as experimental, theoretical, and numerical studies [24]. Several experimental studies

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Surface Backscattering Strengths Measured over an Extended Range of Frequencies and Grazing Angles

Cited by 30 publications

References 0 publications

A Stratified Acoustic Model Accounting for Phase Shifts for Underwater Acoustic Networks

A Stratified Acoustic Model Accounting for Phase Shifts for Underwater Acoustic Networks

NCPA Planning, Organization and Research FY 92

Low Frequency Sound Scattering from Rough Bubbly Ocean Surface: Small Perturbation Theory Based on the Reformed Helmholtz-Kirchhoff-Fresnel Method

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