Download or read book Infragravity Waves Over Topography written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Support from the Office of Naval Research (Coastal Geosciences Program, N00014-02-10145), the National Science Foundation (Physical Oceanography, OCE-0115850).
Download or read book Infragravity Waves in the Nearshore Zone written by Kent K. Hathaway and published by . This book was released on 1998 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the present state of knowledge on infragravity wave motions (nominally 0.003 to 0.05 Hz). Theoretical and observational studies are presented. Most of the studies discussed herein have been published elsewhere, however a few studies discussed in chapter 4 are presented for the first time in this report Measurements of nearshore waves and currents have shown that a significant amount of the total energy can be contained in the infragravity band, and on highly dissipative beaches the infragravity wave variance often dominates over energy in the incident wave band(0.05 to 0.3 Hz). An 8-month data set of infragravity variance measured at 8-m-depth at the shoreline (runup) was compared with incident wave variance. Analysis of the 8-m-depth data showed that high mode edge waves account for about 50 percent of the total infragravity variance, and as high as 80 percent at times. Significant edge wave heights greater than 20 cm were observed at the 8-m depth. Infragravity wave variance was shown to have a higher correlation with swell variance (C = 0.95) than with sea variance (C = 0.61). This report was motivated, in part, by the need to determine the significance of infragravity waves on coastal erosion and structure damage and by the desire to improve coastal engineering solutions to problems associated with nearshore processes.
Download or read book Numerical Modelling of Infragravity Waves written by Arshad Rawat and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind-generated surface gravity waves are ubiquitous at the ocean surface. Their period varies between 2 and 25 seconds, with wavelength varying between a few meters to several hundreds of meters. Longer and, lower frequency surface gravity waves, called infragravity (IG) waves, are associated to these short, high frequency wind-generated waves. These infragravity waves have dominant periods comprised between 30 seconds and 10 minutes, and, when they propagate freely, with horizontal wavelengths of up to tens of kilometres, as given by the linear surface gravity wave dispersion relation. Outside of surf zones, the vertical amplitude of these infragravity waves is of the order of 1-10 cm, while the amplitude of wind-generated waves is of the order of 1-10 m.Given the length scales of the infragravity wavelengths, and despite the fact that the infragravity wave field exhibits much smaller vertical amplitudes than the high frequency wind-driven waves, the infragravity wave field will be a significant fraction the signal measured by the future Surface Water Ocean Topography satellite (SWOT) mission. This infragravity wave field will have to be characterized in order to achieve the expected precision on dynamic height measurements. It appears likely that the above mentioned precision will not be feasible for high sea states and long and steep swells. One of the aims of this thesis was to provide a first quantification of these associated uncertainties. Beyond the SWOT mission, the quantification of the IG wave field is a key problem for the understanding of several geophysical phenomena, such as the understanding of microseisms and ice shelves break up.
Download or read book Infragravity Waves Generated Through Shoaling and Breaking of Wave Groups written by Sriram Sivaram and published by . This book was released on 1992 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Topographic and Rotation Effects on Gravity Wave Dynamics in the Atmosphere written by Triantaphyilos R. Akylas and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical models for the generation of gravity internal waves by flow over topography have been developed, in an effort to understand the role of orographically induced gravity waves in atmospheric turbulence production. For given background wind speed and distribution of buoyancy frequency, the location of the tropopause (the borderline between the troposphere and the stratosphere) is found to have a significant effect, consistent with observations of increased gravity-wave activity over New Mexico when the tropopause is 10-11 km above ground. Based on a finite-amplitude hydrostatic model that accounts for three dimensional effects, a theoretical explanation has been proposed for certain intense oblique gravity wave trains observed downstream of islands. Finally, the effects of periodic variations in the background buoyancy frequency have been studied, Under certain conditions, such fluctuations are found to cause trapping of mountain waves well below the tropopause while, in other instances, they result in unusually strong gravity-wave activity owing to a resonance phenomenon.
Download or read book Bound Infragravity Waves written by and published by . This book was released on 1992 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model predictions of bound (i.e., nonlinearly forced by and coupled to wave groups) infragravity wave energy am compared with about 2 years of observations in 8- to 13-m depths at Imperial Beach, California, and Barbers Point, Hawaii. Frequency-directional spectra of free waves at sea and swell frequencies, estimated with a small array of four pressure sensors, are used to predict the bound wave spectra below 0.04 Hz. The predicted total bound wave energy is always less than the observed infragravity energy, and the underprediction increases with increasing water depth and especially with decreasing swell energy. At most half, and usually much less, of the observed infragravity energy is bound. Bound wave spectra are also predicted with data from a single wave gage in 183-m depth at Point Conception, California, and the assumption of unidirectional sea and swell. Even with energetic swell, less than 10% of the total observed infragravity energy in 183-m depth is bound. Free waves, either leaky or edge waves, are more energetic than bound waves at both the shallow and deep sites. The low level of infragravity energy observed in 183-m depth compared with 8- to 13-m depths, with similarly moderate sea and swell energy, suggests that leaky (and very high-mode edge) waves contribute less than 10% of the infragravity energy in 8-13 m. Most of the free infragravity energy in shallow water is refractively trapped and does not reach deep water.
Download or read book Infragravity Waves and Nearshore Bars written by Troels Aagaard and published by . This book was released on 1989 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Topographic and Rotation Effects on Gravity Wave Dynamics in the Atmosphere written by Triantaphyilos R. Akylas and published by . This book was released on 2001 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shore Wave Modulation Due to Infragravity Waves in the Nearshore Zone with Applications written by Saad M. M. Abdelrahman and published by . This book was released on 1986 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: The omni-present low frequency wave motion (30-300 sec) contains a substantial fraction of the total wave energy inside the surf zone. A more complete description of nearshore wave processes considers incident short period waves superposed on, and interacting with, long standing waves. The wind waves are modulated in amplitude, wavenumber and direction due to relatively slowly varying depth changes caused by the long waves. The energy in the wind wave band is enhanced by side band growth at the sum and difference frequencies of short and long waves (order 15% at the shoreline). The modulation is identified in the analysis of field data as a positive correlation between the long waves and the wind wave envelope near the shoreline. Considering oblique incident waves, a steady longshore current showing a non-vanishing current at the shoreline is found as a result of the non-linear interaction between monochromatic incident and infragravity waves. An analytical solution describing the unsteadiness of the longshore current is developed. Keywords include: Infragravity, Longshore Current, Sediment transport, and Surf zone dynamics. (Theses).
Download or read book Infragravity Waves in a Dissipative Multiple Bar System written by Bernard Gerhard Ruessink and published by . This book was released on 1998 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Infragravity Waves in the Nearshore Zone written by Kent K. Hathaway and published by . This book was released on 1998 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the present state of knowledge on infragravity wave motions (nominally 0.003 to 0.05 Hz). Theoretical and observational studies are presented. Most of the studies discussed herein have been published elsewhere, however a few studies discussed in chapter 4 are presented for the first time in this report Measurements of nearshore waves and currents have shown that a significant amount of the total energy can be contained in the infragravity band, and on highly dissipative beaches the infragravity wave variance often dominates over energy in the incident wave band(0.05 to 0.3 Hz). An 8-month data set of infragravity variance measured at 8-m-depth at the shoreline (runup) was compared with incident wave variance. Analysis of the 8-m-depth data showed that high mode edge waves account for about 50 percent of the total infragravity variance, and as high as 80 percent at times. Significant edge wave heights greater than 20 cm were observed at the 8-m depth. Infragravity wave variance was shown to have a higher correlation with swell variance (C = 0.95) than with sea variance (C = 0.61). This report was motivated, in part, by the need to determine the significance of infragravity waves on coastal erosion and structure damage and by the desire to improve coastal engineering solutions to problems associated with nearshore processes.
Download or read book Short Wave Modulation Due to Infragravity Waves in the Nearshore Zone with Applications written by Saad M. M. Abdelrahman and published by . This book was released on 1986 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Forced Vortex Dynamics in the Surf Zone written by Joseph D. Geiman and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A relation between the spectra of the forcing and the spectra of the fluid response is a primary goal in all areas of fluid dynamics. In the surf zone, these efforts are made somewhat more difficult, due to the large range of temporal scales that must be resolved as well as the interaction between 2D divergent phenomena (surface gravity waves, infragravity waves, edge waves, tidal waves) and shear flows and eddies, all of which occur simultaneously under strong enough forcing conditions. When topography strongly controls the flow organization, such as on a rip channeled beach, wave and current models with differing forcing mechanisms- either calculating each individual breaking wave crest explicitly, or only calculating the mean wave properties that vary slowly in time and space, are able to reproduce Eulerian and Lagrangian flow statistics close to drifter and current meter observations. Each model agrees with field observations of large, coherent eddies that entrain 10 4 m 3 of water in the nearshore. These circulation cells are strongly tied to the topography, and behave like coupled oscillators even when the wave forcing is monochromatic, and exhibit natural oscillations which depend only on a typical eddy length scale and strength of forcing. When wave groups are incident over the same topography, the resulting vorticity field spectra shows a significant peak at the wave group frequency, due to modulation of the breaker line and wave advection. For a narrow band of frequencies about f = 0.004 Hz, resonant edge waves are generated that also modulate the vorticity field at harmonics of the forcing frequency. The natural oscillations are detectable for all ranges of the wave group forcing frequency, but suppressed when the rip current system is forced near resonance.
Download or read book Waves in Oceanic and Coastal Waters written by Leo H. Holthuijsen and published by Cambridge University Press. This book was released on 2010-02-04 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Waves in Oceanic and Coastal Waters describes the observation, analysis and prediction of wind-generated waves in the open ocean, in shelf seas, and in coastal regions with islands, channels, tidal flats and inlets, estuaries, fjords and lagoons. Most of this richly illustrated book is devoted to the physical aspects of waves. After introducing observation techniques for waves, both at sea and from space, the book defines the parameters that characterise waves. Using basic statistical and physical concepts, the author discusses the prediction of waves in oceanic and coastal waters, first in terms of generalised observations, and then in terms of the more theoretical framework of the spectral energy balance. He gives the results of established theories and also the direction in which research is developing. The book ends with a description of SWAN (Simulating Waves Nearshore), the preferred computer model of the engineering community for predicting waves in coastal waters.
Download or read book Nearshore and Surf Zone Morphodynamics A Global Environmental Model for Predicting Hazards and Changes Appendix 6 Standing Waves on a Pronounced Bar Trough Beach written by Nungjane C. Shi and published by . This book was released on 1985 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hypothesis that a pronounced bar-trough surf zone topography favors resonance of standing waves with antinodes located over the bar is examined. Numerical and field investigations of standing waves in a bar-trough surf zone suggest a selective trapping of wave energy at specific resonant frequencies in the subharmonic and the high frequency infragravity bands and a possible suppression of lower frequencies. The resonant frequencies predicted by the numerical model remain fairly constant throughtout the tidal cycle due to the small tidal range typically associated with a bar-trough beach. Cross-shore bar migration changes the resonant frequencies. Numerical simulations show that an onshore bar migration is accompanied by a reduction in the period of the resonant wave and a decrease in the longshore wavelength of the possible edge wave mode.
Download or read book Coastal Engineering 2006 written by Jane McKee Smith and published by . This book was released on 2007 with total page 1128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Proceedings contains 445 papers presented at the 30th International Conference on Coastal Engineering, which was held in San Diego, California, USA, 3-8 September 2006. The Proceedings is divided into five parts: Waves; Swash, Nearshore Currents, and Long Waves; Coastal Management, Risk, and Ecosystem Restoration; Sediment Transport and Morphology; and Coastal Structures. The individual papers cover a broad range of topics including theory, numerical and physical modeling, field measurements, case studies, design, and management. These papers provide engineers, scientists, and planners state-of-the-art information on coastal engineering and coastal processes.
