Statistical modeling of very shallow water/surf zone underwater communications channels

2001 ◽  
Vol 109 (5) ◽  
pp. 2450-2450
Author(s):  
Dale Green
Keyword(s):  
Shallow Water ◽  
Statistical Modeling ◽  
Surf Zone ◽  
Underwater Communications

scholarly journals PROBABILITIES OF BREAKING WAVE CHARACTERISTICS

1970 ◽  
Vol 1 (12) ◽  
pp. 25 ◽  
Author(s):  
J. Ian Collins
Keyword(s):  
Shallow Water ◽  
Probability Density ◽  
Deep Water ◽  
Surf Zone ◽  
Probability Distributions ◽  
Rayleigh Distribution ◽  
Breaking Wave ◽  
Wave Characteristics ◽  
Probability Densities ◽  
Wave Heights

Utilizing the hydrodynamic relationships for shoaling and refraction of waves approaching a shoreline over parallel bottom contours a procedure is developed to transform an arbitrary probability density of wave characteristics in deep water into the corresponding breaking characteristics in shallow Water A number of probability distributions for breaking wave characteristics are derived m terms of assumed deep water probability densities of wave heights wave lengths and angles of approach Some probability densities for wave heights at specific locations in the surf zone are computed for a Rayleigh distribution in deep water The probability computations are used to derive the expectation of energy flux and its distribution.

Robustness of nearshore vortices

2018 ◽  
Vol 850 ◽  
Author(s):  
James C. McWilliams ◽  
Cigdem Akan ◽  
Yusuke Uchiyama
Keyword(s):  
Shallow Water ◽  
Surf Zone ◽  
3D Models ◽  
Density Stratification ◽  
Water Model ◽  
Shallow Water Model ◽  
Dynamical Models ◽  
Coherent Vortices ◽  
Dipole Vortex ◽  
Sloping Beach

Coherent vortices with horizontal swirl arise spontaneously in the wave-driven nearshore surf zone. Here, a demonstration is made of the much greater robustness of coherent barotropic dipole vortices on a sloping beach in a 2D shallow-water model compared with fully 3D models either without or with stable density stratification. The explanation is that active vortex tilting and stretching or instability in 3D disrupt an initially barotropic dipole vortex. Without stratification in 3D, the vorticity retains a dipole envelope structure but is internally fragmented. With stratification in 3D, the disrupted vortex reforms as a coherent but weaker surface-intensified baroclinic dipole vortex. An implication is that barotropic or depth-integrated dynamical models of the wave-driven surf zone misrepresent an important aspect of surf-eddy behaviour.

Big fish in shallow water; use of an intertidal surf-zone habitat by large-bodied teleosts and elasmobranchs in tropical northern Australia

2013 ◽  
Vol 97 (7) ◽  
pp. 821-838 ◽  
Author(s):  
Andrew J. Tobin ◽  
Amos Mapleston ◽  
Alastair V. Harry ◽  
Mario Espinoza
Keyword(s):  
Shallow Water ◽  
Water Use ◽  
Surf Zone ◽  
Northern Australia

A Parametric Study of Sound Focusing in Shallow Water by Using Acoustic Contrast Control

2014 ◽  
Vol 22 (04) ◽  
pp. 1450012 ◽  
Author(s):  
Yi-Wei Lin ◽  
Gee-Pinn James Too
Keyword(s):  
Shallow Water ◽  
Frequency Control ◽  
Control Process ◽  
Environmental Parameters ◽  
Specific Area ◽  
Underwater Communications ◽  
Control Zone ◽  
Sound Energy ◽  
Shift Keying ◽  
And Control

Acoustic contrast control is a sound focusing technique applied to personal audio system devices to provide the optimal sound contrast for increasing or decreasing the potential sound energy of a specific area. In this study, acoustic contrast control was developed for sound focusing in shallow water. The advantage of this technique is the establishment of two zones: a bright zone around the user and a dark zone for other regions. In the acoustic contrast control process, computational ocean acoustics are used to calculate the Green's function between the source point and the field point. The effects of environmental parameters, which comprised the number of control sources, transmission frequency, control distances between sources and control zone of a geometric location were simulated. The results show that acoustic contrast control is an effective approach for sound focusing in shallow water that can increase the potential sound energy of a specific area. Employing this technique can also enhance underwater communications by using frequency-shift keying modulation for cross-talking applications.

An Arctic-Type Shallow-Water Acoustic Waveguide as an Information Transmission Channel for Underwater Communications

2018 ◽  
Vol 64 (6) ◽  
pp. 692-697 ◽  
Author(s):  
M. V. Volkov ◽  
V. A. Grigor’ev ◽  
I. V. Zhilin ◽  
A. A. Lunkov ◽  
V. G. Petnikov ◽  
...  
Keyword(s):  
Information Transmission ◽  
Shallow Water ◽  
Transmission Channel ◽  
Underwater Communications ◽  
Acoustic Waveguide

Rapid overt airborne reconnaissance (ROAR) for mines and obstacles in very shallow water, surf zone, and beach

2003 ◽  
Author(s):  
Steven E. Moran ◽  
William L. Austin ◽  
James T. Murray ◽  
Nicolas A. Roddier ◽  
Robert Bridges ◽  
...  
Keyword(s):  
Shallow Water ◽  
Surf Zone

scholarly journals MODIFICATION OF WAVE SPECTRA ON THE CONTINENTAL SHELF AND IN THE SURF ZONE

2011 ◽  
Vol 1 (8) ◽  
pp. 2 ◽  
Author(s):  
Charles L. Bretschneider
Keyword(s):  
Continental Shelf ◽  
Shallow Water ◽  
Surf Zone ◽  
Wind Waves ◽  
Wave Spectrum ◽  
Breaking Waves ◽  
Bottom Friction ◽  
Breaking Wave ◽  
Predominant Period ◽  
Significant Period

This paper discusses the problem pertaining to the modification of the wave spectrum over the continental shelf. Modification factors include bottom friction, percolation, refraction, breaking waves, ocean currents, and regeneration of wind waves in shallow water, among other factors. A formulation of the problem is presented but no general solution is made, primarily because of lack of basic data. Several special solutions are presented based on reasonable assumptions. The case for a steep continental shelf with parallel bottom contours and wave crests parallel to the coast and for which bottom friction is neglected has been investigated. For this case it is found that the predominant period shifts toward longer periods. The implication is, for example, that the significant periods observed along the U. S. Pacific coast are longer than those which would be observed several miles westward over deep water. The case for a gentle continental shelf with parallel bottom contour and wave crests parallel to the coast and for which bottom friction is important has also been investigated. For this case it is found that the predominant period shifts toward shorter periods as the water depth decreases. The implication is, for example, that the significant periods observed in the shallow water over the continental shelf are shorter than those which would be observed beyond the continental slope. In very shallow water, because shoaling becomes important, a secondary peak appears at higher periods. The joint distribution of wave heights and wave periods is required in order to determine the most probable maximum breaking wave, which can be of lesser height than the most probable maximum non-breaking wave. In very shallow water the most probable maximum breaking wave which first occurs would be governed by the breaking depth criteria, whereas in deepwater wave steepness can also be a governing factor. It can be expected that in very shallow water the period of the most probable maximum breaking wave should be longer than the significant period; and for deeper water the period of the most probable maximum breaking wave can be less than the significant period.

scholarly journals CLOSED-FORM SOLUTIONS FOR THE PROBABILITY DENSITY OF WAVE HEIGHT IN THE SURF ZONE

1988 ◽  
Vol 1 (21) ◽  
pp. 60 ◽  
Author(s):  
William R. Dally ◽  
Robert G. Dean
Keyword(s):  
Probability Density Function ◽  
Shallow Water ◽  
Closed Form ◽  
Probability Density ◽  
Density Function ◽  
Wave Height ◽  
Surf Zone ◽  
Wave Steepness ◽  
Bottom Slope ◽  
Closed Form Solutions

By invoking the assumption that in the surf zone, random waves behave as a collection of individual regular waves, two closed-form solutions for the probability density function of wave height on planar beaches are derived. The first uses shallow water linear theory for wave shoaling, assumes a uniform incipient condition, and prescribes breaking with a regular wave model that includes both bottom slope and wave steepness effects on the rate of decay. In the second model, the shallow water assumption is removed, and a distribution in wave period (incipient condition) is included. Preliminary results indicate that the models exhibit much of the behavior noted for random wave transformation reported in the literature, including bottom slope and wave steepness effects on the shape of the probability density function.

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