Video observations and model predictions of depth-induced wave dissipation

Aarninkhof, S.G.J.; Ruessink, Gerben

doi:10.1109/tgrs.2004.835349

Cited by 41 publications

(48 citation statements)

References 27 publications

(68 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Sinnett and Feddersen (2016) surfzone foam coverage model is similar to the breaking wave intensity model, as measured by whiteness (as an indication of foam) in video images by Aarninkhof and Ruessink (2004), who also find the breaking intensity is related to the roller energy dissipation. Examples of the wave height and d f are provided in Figs.…”

Section: Surfzone Foam Coverage Drag Coefficient Modelsupporting

confidence: 63%

Increased Aerodynamic Roughness Owing to Surfzone Foam

MacMahan

2017

Journal of Physical Oceanography

View full text Add to dashboard Cite

Drag coefficients Cd obtained through direct eddy covariance estimates of the wind stress were observed at four different sandy beaches with dissipative surfzones along the coastline of Monterey Bay, California. The measured surfzone Cd (~2 × 10−3) is twice as large as open-ocean estimates and consistent with recent estimates of Cd over the surfzone and shoaling region. Owing to the heterogeneous nature of the near shore consisting of nonbreaking shoaling waves and breaking surfzone waves, the surfzone wind stress source region is estimated from the footprint probability distribution derived for stable and unstable atmospheric conditions. An empirical model developed for estimating the Cd for open-ocean foam coverage dependent on wind speed is modified for foam coverage owing to depth-limited wave breaking within the surfzone. A modified empirical Cd model for surfzone foam predicts similar values as the measured Cd and provides an alternative mechanism to describe roughness.

show abstract

Section: Surfzone Foam Coverage Drag Coefficient Modelsupporting

confidence: 63%

Increased Aerodynamic Roughness Owing to Surfzone Foam

MacMahan

2017

Journal of Physical Oceanography

View full text Add to dashboard Cite

show abstract

“…Despite the presence of foam, to date, the main procedure that is used to denote zones of preferential breaking involves the use of time exposures where the contributions of the wave roller and remnant foam are intermingled. Aarninkhof and Ruessink [35] developed a procedure that is used to remove the foam contribution from the mean intensity image (or time exposure) during postprocessing by introducing a model for the decay of the intensity signal, but a separation methodology applicable on a wave-by-wave basis does not yet exist.…”

Section: A Opticalmentioning

confidence: 99%

“…This departure from the expected Gaussian distribution of the nonbreaking waves has been used by Mironov and Dulov [23] to discriminate between wave breaking stages in deep water. In the surf zone, Aarninkhof and Ruessink [35] introduced a model relating the time series of the optical intensity to the wave period T and a parameter that is related to foam persistence (λ). A pdf can be derived for this model…”

Section: A Opticalmentioning

confidence: 99%

Optical and Microwave Detection of Wave Breaking in the Surf Zone

Catalán¹,

Haller

Holman

et al. 2011

IEEE Trans. Geosci. Remote Sensing

View full text Add to dashboard Cite

Abstract-Synchronous and colocated optical and microwave signals from waves in the surf zone are presented and analyzed. The field data were collected using a high-resolution video system and a calibrated horizontally polarized marine radar during the decaying phase of a storm. The resulting changes in the received signals from varying environmental conditions were analyzed. The analysis of the optical signal histograms showed functional shapes that were in accordance with the expected imaging mechanisms from the breaking and nonbreaking waves. For the microwave returns, the histogram shape showed a little dependence on the environmental parameters and exhibited an inflexion point at high returned power that is attributed to a change in the scattering mechanism. The high intensity signals were clearly associated with active wave breaking. However, with either sensor, it can be difficult to effectively isolate the wave breaking signature from other sources, such as a remnant foam or the highly steepened nonbreaking waves. A combined method was developed using the joint histograms from both sensors, and it is shown to effectively discriminate between active breaking, remnant foam, and steepened waves. The new separation method allows a further analysis of the microwave scattering from the breaking waves and a better quantification of the length scales of the breaking wave roller and the spatial/temporal distribution of wave breaking and wave dissipation in the surf zone.

show abstract

“…To determine whether the rig was located beneath nonbreaking waves or in the outer or inner surf, we examined 10-min timeexposure video images of the study site collected concurrently with the rig measurements (Almar et al 2010). The most conspicuous elements in such images are white, high-intensity bands induced by the foam on the front face of breaking waves, with the magnitude of the intensity related to the degree (i.e., frequency of occurrence) of wave breaking (e.g., Van Enckevort and Ruessink 2001;Aarninkhof and Ruessink 2004). Based on visual observations in the field, images with the rig submerged below a high-intensity band were interpreted as conditions when (virtually) all waves were breaking and were labeled as ''inner surf zone.''…”

Section: Experimental Conditionsmentioning

confidence: 99%

Observations of Turbulence within a Natural Surf Zone

Ruessink

2010

Journal of Physical Oceanography

View full text Add to dashboard Cite

Here, the Reynolds stresses hu9w9i and hy9w9i, where u9, y9, and w9 are the cross-shore, alongshore, and vertical turbulence velocities, respectively, and the angle brackets represent time averaging, are used to diagnose turbulence dynamics beneath natural breaking surf-zone waves. The data were collected at Truc Vert Beach, France, during a 12-day period in 1-3-m water depth with strong cross-shore and alongshore currents under high-energy wave conditions (offshore significant wave heights ranged between 2 and 8 m). The hu9w9i term is predominantly negative, increases with the ratio of wave height H s to water depth h (;degree of wave breaking), and decreases in magnitude toward the bed. This supports the view that the cross-shore shear stress is due to breaking-induced vortices that transport high-speed cross-shore flow downward and disintegrate close to the bed. The occasional positive sign of hu9w9i within the lower 15%-20% of the water column indicates that sometimes surface-generated turbulence is overwhelmed by bed-generated turbulence, but the conditions when this happens are not clear from the data. The term hy9w9i is persistently of opposite sign to the alongshore mean current and decreases with height above the seabed, implying that hy9w9i is due to bottom boundary layer processes rather than surface-generated turbulence. The bottom drag coefficient amounted to 1.6 3 10 23 , similar to earlier observations. As in other high-Reynolds-number geophysical flows, time series of u9w9 and y9w9 comprise intermittently large, short-duration (here, ;1 s) stress events that in the data contribute considerably to the net stress in only 3%-15% of the time. The data further show that the turbulent kinetic energy is depth uniform and increases with H s /h. The depth-averaged Froudescaled turbulent kinetic energy beneath surf-zone bores is 0.025, a factor of 2 to 3 less than observed beneath regular laboratory waves.

show abstract

Video observations and model predictions of depth-induced wave dissipation

Cited by 41 publications

References 27 publications

Increased Aerodynamic Roughness Owing to Surfzone Foam

Increased Aerodynamic Roughness Owing to Surfzone Foam

Optical and Microwave Detection of Wave Breaking in the Surf Zone

Observations of Turbulence within a Natural Surf Zone

Contact Info

Product

Resources

About