Remote sensing of nearshore wave interference

Smit, Pieter; Bland, R.; Janssen, T. T.; Laughlin, Bruce

doi:10.1002/2016jc011705

Cited by 7 publications

(24 citation statements)

References 30 publications

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“…Effects of the wave coherence on the wave setup and extreme wave runup values are important, because of their effects on the morphological changes (Dalrymple & Lanan, 1976). Moreover, wave setup and runup can also be used as efficient measures of wave coherence in field experiments when using an array of wave gauges for the wave coherence recording seems impractical (Smit et al., 2016). Overall, wave coherence can potentially affect many nearshore processes and can deviate them from the analytical solutions.…”

Section: Discussionmentioning

confidence: 99%

Effects of Wave Coherence on Longshore Variability of Nearshore Wave Processes

et al. 2021

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Since Young's (1802) double-slit experiment with optical waves, wave coherence has been studied in various scientific fields including quantum mechanics and engineering. Wave coherence happens when two intersecting waves have identical wave frequency, waveform, and constant phase difference and result in a stationary wave interference in the wavefield. Despite the importance of the subject in various scientific fields, it has not been studied broadly for the water waves. In one of the earliest studies of coherent waves, Dalrymple (1975) investigated the longshore variation of the mean water level as well as the wave height and wave-induced circulation due to the existence of intersecting waves with equal frequencies. He showed that alongshore variation of wave height due to the presence of two coherent waves results in nodal and anti-nodal points alongshore, and rip currents are formed at nodal lines with zero wave height. Following his work, Z. Wei and Dalrymple (2017) carried out numerical experiments with the Lagrangian-based smooth particle hydrodynamics (SPH) model using two intersecting waves of the same period and confirmed the

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Section: Discussionmentioning

confidence: 99%

Effects of Wave Coherence on Longshore Variability of Nearshore Wave Processes

et al. 2021

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“…If both wave trains have the same period, for instance due to focusing on some bathymetric feature that generates a coherent bidirectional wave system, the interference waves do present a spatially periodical stationary pattern. This fact is well described by Smit et al (2016), who used X-band radar observations collected at Ocean Beach, San Francisco, and succeeded in identifying coherent interference of noncollinear waves in the nearshore area during the incidence of long-period swell, propagating over offshore shoals.…”

Section: Shoaling and Refractionmentioning

confidence: 65%

Directional Infragravity Waves Induced by Bichromatic and Bidirectional Waves: Theoretical Approach and Experimental Affirmation

Silva¹,

Kerpen

Rosman

et al. 2022

J. Waterway, Port, Coastal, Ocean Eng.

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This work presents a theoretical discussion and experimental results about the directional bound waves generated by second-order nonlinear interaction between two noncollinear wave trains. Research focus is set on presence, characteristics, and effects of the angle difference between the primary wave trains on the generation of super-and subharmonic bound wave components as well as propagation direction, orbital velocity, and the resulting radiation stress field. An analytical model is derived, and computations thereof conducted for different conditions of wave height, period, and depth. Laboratory tests, systematically conducted in a wave basin, confirm computational results from analytical formulation and indicate that (i) the magnitude of all second-order properties (setup and setdown of the mean water level, orbital velocities) are strongly dependent on the individual combination of periods and directions of the primary wave trains, (ii) the direction of the bound wave differs from those of the primary waves, and (iii) the radiation stress components show a spatial and temporal oscillatory pattern outside the surf zone.

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“…The spatial variation of

H_{s}

in cross wave (

x

) direction is apparent in Figure c. A spatial scale related to coherent interference,

λ

, can be calculated according to Smit et al (), where

λ = 2 π false| normalΔ k_{12}^{x} {false|}^{- 1}

and

normalΔ k_{12}^{x}

is the wavenumber difference of two primary wave components (i.e.,

N = 2

in equation ). The red shadings represent the one standard deviation of

H_{s}

in spatial domain of

λ

, and the observations lie within this range.…”

Section: Resultsmentioning

confidence: 99%

“…There have been a few studies demonstrating the significance of the coherent interference for wave statistics over coastal bathymetry. A series of studies by Smit and Janssen (2013) and Smit et al (2016) have demonstrated that the smaller-scale variability of observed wave height can be well explained by the effect of coherent interference over submarine canyons off the La Jolla, CA, USA, and the San Francisco bar at Ocean Beach, CA, USA. We show here that a coherent wavefield is generated over the continental shelf, and coherent interference is the missing piece of the puzzle for understanding the modulation of local wave statistics and the formation of the large-amplitude waves.…”

Section: Introductionmentioning

confidence: 99%

Phase‐Coherent Amplification of Ocean Swells Over Submarine Canyons

2020

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Ocean swells can be a significant coastal hazard, potentially causing coastal disasters with costly damage to infrastructure and tragic loss of lives. We have observed this in the coastal region of Toyama Bay in the Sea of Japan, which has been devastated by severe winter swell events (the so‐called YoriMawari‐nami; YM wave). An extreme swell event was recorded in February 2008 in which the wave height at a site in the bay reached 9+ m, which corresponds to 16 times the local climatological average. Substantial efforts by the Japanese coastal engineering community have been expended to reproduce YM wave events with phase‐averaged wave models but, to our knowledge, with no success. During an archetype YM event, we found that the Noto peninsula filtered the incoming wavefield such that in the bay incident waves were quasi‐monochromatic. The swell then refracted over a submarine canyon resulting in a bimodal directional distribution of wave energy. This initiated conditions favorable for coherent interference, violating the assumptions of the phase‐averaged approach. Coherent interference is the key mechanism for understanding the formation of the large amplitudes and for matching observed high space‐time variability. Our results demonstrate the significance of the coherent interference for wave statistics over coastal bathymetry; only by accounting for phase‐resolving phenomena were we able to adequately reproduce the observations.

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Remote sensing of nearshore wave interference

Cited by 7 publications

References 30 publications

Effects of Wave Coherence on Longshore Variability of Nearshore Wave Processes

Effects of Wave Coherence on Longshore Variability of Nearshore Wave Processes

Directional Infragravity Waves Induced by Bichromatic and Bidirectional Waves: Theoretical Approach and Experimental Affirmation

Phase‐Coherent Amplification of Ocean Swells Over Submarine Canyons

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