Infragravity-Frequency (0.005–0.05 Hz) Motions on the Shelf. Part II: Free Waves

Herbers, T. H. C.; Elgar, Steve; Guza, R. T.; O’Reilly, W. C.

doi:10.1175/1520-0485(1995)025<1063:ifhmot>2.0.co;2

Cited by 104 publications

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“…Following Elgar and Guza [1985], nonlinear coupling also was estimated from time series of pressure fluctuations containing only shoreward or only seaward propagating infragravity waves (\i + and pT, calculated using r| + and rf (equation (1)), respectively). An error in accounting for the effect of time domain windowing in previously reported bispectral integrals [Herbers et al , 1995aRuessink, 1998] is corrected below, resulting in (i, \i + , and \x~ values that are a factor of 0.58 lower than uncorrected values.…”

Section: Field Experiments and Analysismentioning

confidence: 99%

“…Shoreward propagating waves are assumed to be partially reflected at the shoreline, with the WKB phases e+-€_ = -IT/2 determined by matching to exact standing wave solutions [Herbers et al, 1995a]. Using equation (A2), the autospectra and cross-spectra for collocated pressure and cross-shore velocity time series are 14)).…”

Section: Appendix A: Error Estimates For Jrmentioning

confidence: 99%

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Observations of Nearshore Infragravity Waves: Seaward and Shoreward Propagating Components

Sheremet¹,

Guza²,

Elgar³

et al. 2002

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information The variation of seaward and shoreward infragravity energy fluxes across the shoaling and surf zones of a gently sloping sandy beach is estimated from field observations and related to forcing by groups of sea and swell, dissipation, and shoreline reflection. Data from collocated pressure and velocity sensors deployed between 1 and 6 m water depth are combined, using the assumption of cross-shore propagation, to decompose the infragravity wave field into shoreward and seaward propagating components. Seaward of the surf zone, shoreward propagating infragravity waves are amplified by nonlinear interactions with groups of sea and swell, and the shoreward infragravity energy flux increases in the onshore direction. In the surf zone, nonlinear phase coupling between infragravity waves and groups of sea and swell decreases, as does the shoreward infragravity energy flux, consistent with the cessation of nonlinear forcing and the increased importance of infragravity wave dissipation. Seaward propagating infragravity waves are not phase coupled to incident wave groups, and their energy levels suggest strong infragravity wave reflection near the shoreline. The cross-shore variation of the seaward energy flux is weaker than that of the shoreward flux, resulting in cross-shore variation of the squared infragravity reflection coefficient (ratio of seaward to shoreward energy flux) between about 0.4 and 1.5. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. C8, 10.1029/2001JC000970, 2002 Observations of nearshore infragravity waves: Seaward and shoreward propagating components [I] The variation of seaward and shoreward infragravity energy fluxes across the shoaling and surf zones of a gently sloping sandy beach is estimated from field observations and related to forcing by groups of sea and swell, dissipation, and shoreline reflection. Data from collocated pressure and velocity sensors deployed between 1 and 6 m water depth are combined, using the assumption of cross-shore propagation, to decompose the infragravity wave field into shoreward and seaward propagating components. Seaward of the surf zone, shoreward propagating infragravity waves are amplified by nonlinear interactions with groups of sea and swell, and the shoreward infragravity energy flux increases in the onshore direction. In the surf zone, nonlinear phase coupling between infragravity waves and groups of sea and swell decreases, as does the shoreward infragravity energy flux, consistent with the cessation of nonlinear forcing and the increased impo...

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Section: Field Experiments and Analysismentioning

confidence: 99%

Section: Appendix A: Error Estimates For Jrmentioning

confidence: 99%

Observations of Nearshore Infragravity Waves: Seaward and Shoreward Propagating Components

Sheremet¹,

Guza²,

Elgar³

et al. 2002

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“…This is depicted in Fig. 6 of Herbers et al (1995b). An obvious implication of a broad directional 20 distribution is the presence of alongshore propagation of infragravity waves, which manifest in the form of edge waves that are refractively trapped within the continental shelf.…”

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confidence: 98%

“…Section 3 of Baldock (2012) provides a critical review of these theories relating to the evolution of free waves for further reference. Regardless of their origin or generation, they can propagate in both incident and reflected directions 5 (i.e., toward and outward from the coast), and depending on the incoming wave obliqueness and a geological setting (e.g., continental shelf width and bottom slope), they can escape to deep water as leaky waves or are refractively trapped within the continental shelf as edge waves (Herbers et al, 1995b).…”

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In situ observations of infragravity wave directionality at nearshore coastal sites

Nose

Babanin

Ewans³

2017

Preprint

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Abstract. 'Infragravity waves' is a term used to collectively describe surface gravity waves with periods arbitrarily between 30 and 300 s. In situ observations of infragravity waves at nearshore sites are scarce, and the directionality of the wave field has not received much attention in the past. This paper details a systematic directional analysis of experimental infragravity wave data. Through applying conventional and new directional analysis methods, qualitative and some quantitative characteristics of infragravity wave directions have been resolved. The analysis has found that infragravity waves have a bimodal directional 5 structure with the dominant energy distributed in the propagation sector incident to the coast. It has also been demonstrated that mean infragravity wave directions can be derived, and there is evidence that the directional spreading of infragravity waves is correlated to their wind-generated wave counterparts. Using a numerical model, the qualitative findings were verified; however, contrary to the observations, the dominant direction of the modelled infragravity waves are in the propagation sector outward from the coast. The results provide improved insights into the directionality of infragravity waves, but the disparity between 10 the dominant directions in the model and observations remains to be resolved.

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Infragravity waves across the oceans

Rawat

Ardhuin

Ballu

et al. 2014

Geophysical Research Letters

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Ocean infragravity (IG) waves are low-frequency waves generated along shorelines by incident seas and swell and with heights of the order of 1 cm in the open ocean. Despite these small amplitudes, they can be of much importance for ice shelf break up and errors in measurements of sea level by future satellite altimeters. A combination of numerical model results and in situ data is used to show that bottom pressure signals in the infragravity frequency band can be dominated by bursts of energy that travel across ocean basins, and can last for several days. Two particularly strong events recorded in 2008 are studied, one in the North-Pacific and the other in the North-Atlantic. It is shown that infragravity waves can travel across whole oceans basins with the signal recorded on the western shores often dominated by IG waves coming from the opposite shore of that same ocean basin.

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Infragravity-Frequency (0.005–0.05 Hz) Motions on the Shelf. Part II: Free Waves

Cited by 104 publications

References 0 publications

Observations of Nearshore Infragravity Waves: Seaward and Shoreward Propagating Components

Observations of Nearshore Infragravity Waves: Seaward and Shoreward Propagating Components

In situ observations of infragravity wave directionality at nearshore coastal sites

Infragravity waves across the oceans

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