Oceanography (Professor Robert Guza), the Naval Research Laboratory – Stennis Space Center [Dr. Todd Holland, Dr. Nathaniel Plant (now at ONR), and Dr...bathymetric data, Marine Geology, 191, 71-86, 2002. Schmidt, W.E., B.T. Woodward, K.S. Millikan , R.T. Guza, B. Raubenheimer, and S. Elgar, A GPS
performed at the Scripps Institution of Oceanography (Professor Robert Guza), the Naval Research Laboratory – Stennis Space Center (Dr. Todd Holland, Dr...Division, Planning Systems Inc., 12 pp., 31 March 2005. Schmidt, W.E., B.T. Woodward, K.S. Millikan , R.T. Guza, B. Raubenheimer, and S. Elgar, A
Water Air Soil Pollut DOI 10.1007/s11270-009-0030-z Measuring Fluorescent Dye in the Bubbly and Sediment-Laden Surfzone David B. Clark · Falk...Feddersen · Melissa M. Omand · R. T. Guza Received: 25 September 2008 / Accepted: 10 February 2009 © The Author(s) 2009. This article is published with open...concentrations (e.g., cascading rivers and streams). D. B. Clark (B) · F. Feddersen · M. M. Omand · R. T. Guza Scripps Institution of Oceanography, UCSD, 9500
Waves in Estuarine Environments James M. Kaihatu Zachry Department of Civil Engineering, Texas A&M University 3136 TAMU College Station, TX...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Texas A&M University,Zachry Department of Civil Engineering,3136 TAMU...marsh vegetation. Coast . Engrg. 83, 82-92. Freilich, M.H., and Guza, R.T., 1984. Nonlinear effects on shoaling surface gravity waves. Phil. Trans
an in-depth introduction, the following overview of related wave theories, models, and observations. B. STATISTICAL DESCRIPTION OF WAVES Waves at the...O’Reilly & Guza, 1993; § II.A). However the ray trajectories followed by wave groups, predicted by the geometrical optics approximation, may be modified...roughness’ regime wave energy dissipation is minimal as bottom velocities are small and turbulence is weak. In the following the magnitude of the wave
has been quantified in many studies with several different airborne lidar systems. Robertson et al. (2007) measured beach erosion caused by Hurricane...Mech., 156, 505–531. Robertson , W., K. Zhang, and D. Whitman, 2007: Hurricane- induced beach change derived from airborne laser mea- surements near...level changes on Southern California beaches. Ph.D. thesis, University of California, San Diego, 155 pp. ——, R. Guza, R. Gutierrez, and R. Seymour
Technology, and Ms. Judy Roughton of College of the Albemarle, Elizabeth City, NC. Dr. R. T. Guza, Scripps Institution of Oceanography, and Mr. Lockhart...that used in the CERC Wave Information Studies (Resio, Vincent, and Corson 1982) to the storm events examined in this report. In conjunction with this...C. L., and Corson , W. D. (1982). "Objective specifi- cation of atlantic ocean wind fields from historical data," WIS Report 4, U.S. Army Engineer
34" Joseph Pedlosky Chairman, Joint Committee for Physical Oceanography 2 Infragravity Waves over Topography: Generation, Dissipation, and Reflection...members and coauthors, Drs. David Chapman, Robert Guza, Thomas Herbers, Steve Lentz, Joseph Pedlosky, Britt Raubenheimer, and Carl Wunsch, have patiently...curve). The 95% confidence interval, based on a X2 distribution with 42 degrees of freedom [ Priestley , 1981], is shown in the upper right corner. 15 1.3
chlrophyl A ( Omand et al, 2009). The dye sampling jetski and fixed fluorometers were deployed at Huntington Beach, as part of the HB06 field experiment...SIO graduate PhD student David Clark, co-advised with Dr Feddersen, is using these observations to characterize surfzone mixing (figure 2). 2...1998 Omand , M., F. Feddersen, D.B. Clark, P.J.S. Franks, J. J. Leichter , and R.T. Guza, The Influence of Bubbles and Sand on Chlorophyll-a
The tenth Five-Year Project of China Earthquake Administration installed about 40 YRY-4 type high-resolution borehole strainmeters over the mainland China in order to enhance its capability of earthquake-forecasting attempt. The strainmeters are installed in rocks at a depth around 40m and resolve strain changes to the order of 10-11. Measurements are sampled every minute. There are four gauges horizontally placed, 45-degree apart, in an YRY-4 strainmeter, whose measurements are denoted as Si (i=1, 2, 3, 4) in our study. The similarity of the two curves of S1 +S3 and S2 +S4 of Guza recordings gives sufficient credit to the data. Among the sites, Guza is located the nearest (about 140km), from the epicentral area of the Wenchuan earthquake. Even months before the earthquake, it had already been noticed at Guza that the initially smooth curves had become badly interfered from time to time by minor steps or unsymmetrical pulses with periods of minutes~hours. The interferences were dominantly compressional and mostly on the order of 10-9. They were not corresponding to weather changes. Other sites are at least 300km away and did not observe such anomalies. A comparison of the interferences with the long-term and coseismic changes shows a good consistence in the sense of strain variety among them, which suggests a tectonic cause of the abnormal signals. High-passed data show obvious relevance of the abnormal signals to the Wenchuan quake in time. They became stronger as the great event approached, reached the highest at the main shock and diminishing while aftershocks have been dying away. We put forth an Overrun Rate Analysis (ORA) to give out a quantitative description of the interferences. The high-passed interferences can be depicted as positive or negative big values overrunning the normal level. Overrun Rate of Numbers, denoted as Ron, is defined as the total number of overrun points in one day, and Overrun Rate of Strength Ros the daily sum of amplitudes of
Polukhina, Oxana; Kurkin, Andrey; Pelinovsky, Efim
The investigation of anomalously large amplitude surface gravity waves on the sea surface (rogue or freak waves), which can appear suddenly and disappear in the same abrupt way, is very extensive in the recent years (see e.g., book [Kharif, Pelinovsky, Slunyaev 2009] and references there). However, any sudden displacements of water level or changes in flow velocities can also appear in the ocean wave motions of other types, including geophysical large-scale fields. The number of observations of such waves is still very small, they are even almost absent, but the investigations of such possible processes seem to be important for the applications. In the present paper the problem of rogue waves is discussed for edge waves in the coastal zone. Such waves belong to the class of topographically trapped waves, which are supposed to play dominant role in the dynamics of oceanic coastal zone. The amplitude of the waves reaches a maximum at the edge, and they are attenuated offshore. Direct visual observations of such waves are difficult, but such waves have been detected instrumentally in the nearshore wave field many times (see e.g. [Huntley and Bowen 1973; Bryan, Hows and Bowen 1998]). Edge waves are often considered as the major factor of the long-term evolution of coastal line, forming the rhythmic crescentic bars [Dolan and Ferm 1968; Bowen and Inman 1971; Guza and Inman 1975; Guza and Bowen 1981; Holman and Bowen 1982; Komar 1998]. In the present paper we summarize the results of the study of the nonlinear mechanisms of possible freak edge wave appearance: nonlinear dispersion enhancement and modulation instability.
Keen, A. S.; Holman, R. A.
Parametric depth-induced-breaking dissipation models have shown great skill at predicting time averaged wave heights across the surf zone. First proposed by Battjes & Janssen (1978), these models balance the incoming wave energy flux with a roller dissipation term. This roller dissipation term is estimated by calculating the dissipation for one characteristic broken wave and then multiplying this quantity by the fraction of broken waves. To describe the fraction of broken waves, a typical assumption asserts that wave heights are nearly Rayleigh distributed [Thornton & Guza (1983)] allowing a sea state to be described by only a few parameters. While many experiments have validated the cross shore wave height profiles, few field experiments have been performed to analyze the probability distribution of breaking wave heights over a barred beach profile. The goal of the present research is to determine the distribution of broken and unbroken wave heights across a natural barred beach profile. Field data collected during the Surf Zone Optics experiment (a Multi-disciplinary University Research Initiative) in Duck, North Carolina, consisted of an array of in-situ pressure sensors and optical remote sensing cameras. Sea surface elevation time series from the in-situ pressure sensors are used here to resolve wave height distributions at multiple locations across the surf zone. Breaking wave height distributions are resolved based upon a combination of the pressure sensor and optically based breaker detection algorithm. Since breaking is easily able to be tracked by video imaging, breaking waves are flagged in the sea surface elevation series and binned into a broken wave height distribution. Results of this analysis are compared with model predictions based upon the Battjes & Janssen (1978), Thornton & Guza (1983) and Janssen & Battjes (2007) models to assess the validity of each wave height distribution model.
Contardo, Stephanie; Symonds, Graham; Segura, Laura
The occurrence of short period wind-sea associated with a diurnal sea breeze, superimposed on longer period swell in South West Western Australia provides an opportunity to observe the response of infragravity (0.01-0.05 Hz) waves, in the nearshore, to both wind-sea and swell forcing. An alongshore array of pressure sensors and a cross-shore array of current velocity and pressure sensors are deployed at Secret Harbour, a barred beach near Perth. The observations show a stronger infragravity response to longer period incident swell than to short period wind-sea. Infragravity waves at Secret Harbour are generated by two mechanisms: breakpoint forcing and bound wave release. Breakpoint forcing is observed with both swell and wind-sea forcing while bound wave release is only observed in the presence of swell. Two mechanisms generate free infragravity waves during swell periods while only one mechanism is in place during wind-sea periods, providing an explanation for the stronger response to swell than wind-sea. Free infragravity waves propagating offshore after reflection at the shoreline are called leaky waves; those which are trapped to the shoreline by refraction are called edge waves. At Secret Harbour, both edge waves and leaky waves are detected. Leaky waves dominate with swell forcing while edge waves dominate with wind-sea forcing. Amongst edge waves, mode 0 waves are found to dominate in the absence of wind-sea, while higher mode edge waves dominate when wind-sea is present. We calculate the expected wavenumber-frequency distribution of edge wave and leaky wave energy, based on resonance conditions, using wave period, incidence angle and directional spreading, as proposed by Bowen and Guza (1978). Observations and predictions are in good agreement. However the model can be improved by quantifying the infragravity energy generated by both infragravity wave generation mechanisms. Bowen, A. J., and R. T. Guza (1978), Edge waves and surf beat, Journal of
Haines, John W.; Sallenger, Asbury H.
Mean cross-shore currents observed across a barred surf zone are compared to model predictions. The model is based on a simplified momentum balance with a turbulent boundary layer at the bed. Turbulent exchange is parameterized by an eddy viscosity formulation, with the eddy viscosity Aυ independent of time and the vertical coordinate. Mean currents result from gradients due to wave breaking and shoaling, and the presence of a mean setup of the free surface. Descriptions of the wave field are provided by the wave transformation model of Thornton and Guza . The wave transformation model adequately reproduces the observed wave heights across the surf zone. The mean current model successfully reproduces the observed cross-shore flows. Both observations and predictions show predominantly offshore flow with onshore flow restricted to a relatively thin surface layer. Successful application of the mean flow model requires an eddy viscosity which varies horizontally across the surf zone. Attempts are made to parameterize this variation with some success. The data does not discriminate between alternative parameterizations proposed. The overall variability in eddy viscosity suggested by the model fitting should be resolvable by field measurements of the turbulent stresses. Consistent shortcomings of the parameterizations, and the overall modeling effort, suggest avenues for further development and data collection.
Apotsos, A. A.; Raubenheimer, B.; Elgar, S.; Guza, R. T.
Seven parametric models for wave height transformation across the surf zone [e.g., Thornton and Guza, 1983] are tested with observations collected between the shoreline and about 5-m water depth during 2 experiments on a barred beach near Duck, NC, and between the shoreline and about 3.5-m water depth during 2 experiments on unbarred beaches near La Jolla, CA. Offshore wave heights ranged from about 0.1 to 3.0 m. Beach profiles were surveyed approximately every other day. The models predict the observations well. Root-mean-square errors between observed and simulated wave heights are small in water depths h > 2 m (average rms errors < 10%), and increase with decreasing depth for h < 2 m (average rms errors > 20%). The lowest rms errors (i.e., the most accurate predictions) are achieved by tuning a free parameter, γ, in each model. To tune the models accurately to the data considered here, observations are required at 3 to 5 locations, and must span the surf zone. No tuned or untuned model provides the best predictions for all data records in any one experiment. The best fit γ's for each model-experiment pair are represented well with an empirical hyperbolic tangent curve based on the inverse Iribarren number. In 3 of the 4 data sets, estimating γ for each model using an average curve based on the predictions and observations from all 4 experiments typically improves model-data agreement relative to using a constant or previously determined empirical γ. The best fit γ's at the 4th experiment (conducted off La Jolla, CA) are roughly 20% smaller than the γ's for the other 3 experiments, and thus using the experiment-averaged curve increases prediction errors. Possible causes for the smaller γ's at the 4th experiment will be discussed. Funded by ONR and NSF.
Ludka, B. C.; Guza, R. T.; McNinch, J. E.; O'Reilly, W.
variations of the wave field (measured immediately offshore) are large, but shoreline changes (usually <30cm) are smaller than in Southern California. Maximum vertical variations occur just seaward of the shoreline and the nearshore bathymetry is often barred. Plant (1999) show that bar crest position at Duck has equilibrium-like behavior. We will present the results of equilibrium shoreline and profile modeling at Duck. At both sites, we diagnose sources (e.g. grain size and incident waves) of the sometimes strong observed alongshore variations in sand level change patterns. Funding was provided by the US Army Corps of Engineers and the California Department of Boating and Waterways. REFERENCES Plant, N. G., R. A. Holman, M. H. Freilich, and W. A. Birkemeier (1999), A simple model for interannual sandbar behavior, J. Geophys. Res., 104(C7), 15,755-15,776. Yates, M. L., R. T. Guza, and W. C. O'Reilly (2009), Equilibrium shoreline response: Observations and modeling, J. Geophys. Res., 114, C09014.
Lopez, Mario; Iglesias, Gregorio
focused on the long waves at the Port of Ferrol and their implications for the operations at the port. References Candella, R.N., Rabinovich, A.B., Thomson, R.E., 2008. The 2004 Sumatra tsunami as recorded on the Atlantic coast of South America. Adv. Geosci. 14, 117-128. Cecioni, C., Bellotti, G., 2010. Modeling tsunamis generated by submerged landslides using depth integrated equations. Appl. Ocean Res. 32(3), 343-350. de Jong, M.P.C., Battjes, J.A., 2004. Low-frequency sea waves generated by atmospheric convection cells. Journal of Geophysical Research-Oceans 109(C1), C01011. López, M., Iglesias, G., 2013. Artificial Intelligence for estimating infragravity energy in a harbour. Ocean Eng. 57(0), 56-63. López, M., Iglesias, G., Kobayashi, N., 2012. Long period oscillations and tidal level in the Port of Ferrol. Appl. Ocean Res. 38(0), 126-134. Okihiro, M., Guza, R.T., Seymour, R.J., 1993. Excitation of Seiche Observed in a Small Harbor. J. Geophys. Res. 98(C10), 18201-18211. Sepic, J., Orlic, M., Vilibic, I., 2008. The Bakar Bay seiches and their relationship with atmospheric processes. Acta Adriat. 49(2).