Wave height

About: Wave height is a research topic. Over the lifetime, 5920 publications have been published within this topic receiving 100257 citations.

Observation of wind-waves from a moored buoy in the Southern Ocean

Abstract: The Southern Ocean is an important component in the global wave climate. However, owing to a lack of observations, our understanding of waves is poor compared to other regions. The Southern Ocean Flux Station (SOFS) has been deployed to fill this gap and represents the first successful moored air-sea flux station at these southern hemisphere latitudes. In this paper, we present for the first time the results from the analysis of the wave measurements, focused on statistics and extremes of the main wave parameters. Furthermore, a spectral characterization is performed regarding the number of wave systems and predominance of swell/wind-sea. Our results indicate a high consistency in terms of wave parameters for all deployments. The maximum significant wave height obtained in the 705 days of observation was 13.41 m. The main spectra found represent unimodal swell dominated cases; however, the dimensionless energy plotted against dimensionless peak frequency for these spectra follows a well-known relation for wind-sea conditions. In addition, the Centre for Australian Weather and Climate Research wave hindcast is validated with the SOFS data.

Shoreline instability under low‐angle wave incidence

Abstract: [1] The growth of megacusps as shoreline instabilities is investigated by examining the coupling between wave transformation in the shoaling zone, longshore transport in the surf zone, cross-shore transport, and morphological evolution. This coupling is known to drive a potential positive feedback in case of very oblique wave incidence, leading to an unstable shoreline and the consequent formation of shoreline sand waves. Here, using a linear stability model based on the one-line concept, we demonstrate that such instabilities can also develop in cases of low-angle or shore normal incidence under certain conditions (small enough wave height and/or large enough beach slope). The wavelength and growth timescales are much smaller than those of high-angle wave instabilities and are nearly in the range of those of surf zone rhythmic bars, O(102–103 m) and O(1–10 days). The feedback mechanism is based on (1) wave refraction by a shoal (defined as a cross-shore extension of the shoreline perturbation) leading to wave convergence shoreward of it; (2) longshore sediment flux convergence between the shoal and the shoreline, resulting in megacusp formation; and (3) cross-shore sediment flux from the surf to the shoaling zone, feeding the shoal. Even though the present model is based on a crude representation of nearshore dynamics, a comparison of model results with existing depth-averaged two-dimensional model output and laboratory experiments suggests that the instability mechanism is plausible. Additional work is required to fully assess whether and under which conditions this mechanism exists in nature.

Breakwater Gap Wave Diffraction: an Experimental and Numerical Study

Abstract: Breakwater gap configurations with gap‐to‐wavelength (B/L) ratios of 1.64, 1.41, 1.20, 1.00, 0.75, and 0.50 are investigated, both experimentally (using close‐range photogrammetry) and numerically (using finite and infinite elements). The experimental results, when compared to the finite element and available analytical results, show that: (1) The measured wave heights in the shadow zones (those regions sheltered by the breakwater arms) tend to be larger than predicted theoretically due to the combined effect of secondary waves generated at the breakwater tips and wave orthogonal spreading near the gap centerline (and subsequent wave orthogonal bunching in the shadow zones) caused by wave steepness differences along the crests; and (2) the wave heights outside the shadow zones tend to be smaller than predicted theoretically, again due to wave orthogonal spreading caused by the greater steepness of waves near the gap centerline. The results suggest that linear theory provides conservative wave height estim...

Changes in wave climate over the northwest European shelf seas during the last 12,000 years

Abstract: [1] Because of the depth attenuation of wave orbital velocity, wave-induced bed shear stress is much more sensitive to changes in total water depth than tidal-induced bed shear stress. The ratio between wave- and tidal-induced bed shear stress in many shelf sea regions has varied considerably over the recent geological past because of combined eustatic changes in sea level and isostatic adjustment. In order to capture the high-frequency nature of wind events, a two-dimensional spectral wave model is here applied at high temporal resolution to time slices from 12 ka BP to present using paleobathymetries of the NW European shelf seas. By contrasting paleowave climates and bed shear stress distributions with present-day conditions, the model results demonstrate that, in regions of the shelf seas that remained wet continuously over the last 12,000 years, annual root-mean-square (rms) and peak wave heights increased from 12 ka BP to present. This increase in wave height was accompanied by a large reduction in the annual rms wave-induced bed shear stress, primarily caused by a reduction in the magnitude of wave orbital velocity penetrating to the bed for increasing relative sea level. In regions of the shelf seas which remained wet over the last 12,000 years, the annual mean ratio of wave- to (M2) tidal-induced bed shear stress decreased from 1 (at 12 ka BP) to its present-day value of 0.5. Therefore compared to present-day conditions, waves had a more important contribution to large-scale sediment transport processes in the Celtic Sea and the northwestern North Sea at 12 ka BP.