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Showing papers on "Wave height published in 2015"


Journal ArticleDOI
TL;DR: Radiance reflectance factors, as used to estimate water-leaving radiance from measured upwelling and sky radiances, are shown to depend on sky polarization, and improved values are given.
Abstract: Generation of random sea surfaces using wave variance spectra and Fourier transforms is formulated in a way that guarantees conservation of wave energy and fully resolves wave height and slope variances. Monte Carlo polarized ray tracing, which accounts for multiple scattering between light rays and wave facets, is used to compute effective Mueller matrices for reflection and transmission of air- or water-incident polarized radiance. Irradiance reflectances computed using a Rayleigh sky radiance distribution, sea surfaces generated with Cox-Munk statistics, and unpolarized ray tracing differ by 10%-18% compared with values computed using elevation- and slope-resolving surfaces and polarized ray tracing. Radiance reflectance factors, as used to estimate water-leaving radiance from measured upwelling and sky radiances, are shown to depend on sky polarization, and improved values are given.

126 citations


Journal ArticleDOI
TL;DR: In this article, a copula-based approach is presented for modeling the joint distribution derived from almost six years of sea levels and waves at a site suffering from coastal flooding at a particular simplified application case is described for the Ravenna coast (Italy).

91 citations


Journal ArticleDOI
TL;DR: In this paper, a fluid-solid coupling model based on general moving objects (GMO) collision model and renormalisation group (RNG) turbulent model were employed, simplifying the sliding motion of the Qianjiangping landslide as a rigid body circular motion whose validity was verified by comparing with actual survey conditions related.
Abstract: The Qianjiangping landslide occurred on July 13, 2003 when water level in the Three Gorges Reservoir in China reached 135 m a.s.l. for about 1 month. Thirteen people on the slope and 11 fishermen on boats in the nearby area were killed by this landslide and its wave. As a typical case, the Qianjiangping landslide is researched extensively, but the wave itself was studied much less. In this paper, a fluid–solid coupling model based on general moving objects (GMO) collision model and renormalisation group (RNG) turbulent model were employed, simplifying the sliding motion of the Qianjiangping landslide as a rigid body circular motion whose validity was verified by comparing with actual survey conditions related. Numerical simulation analysis shows that in the Qianjiangping landslide event, the solid–fluid energy-transferring rate was 5.97 %, while the motion of sliding mass could push and raise water body. The maximum-modelled wave run-up generated by the Qianjiangping landslide was 40.4 m (up to 175.4 m a.s.l.), while the maximal observed one was 39 m. It was the solitary wave, and the wave celerity was 32∼36 m/s or so. The hazardous river length of impulse wave was estimated to be 12.6 km, where wave height was more than 1 m high. The fluid–solid coupling numerical model employed by this paper can provide important reference for wave generated by other landslides around the world. Research of the landslide-generated wave is very significant in landslide hazard reduction and prevention.

88 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated trends in marine wind speed and significant wave height using the global reanalysis ERA-Interim over the period 1979-2012, based on monthly-mean and monthly-maximum data.
Abstract: Trends in marine wind speed and significant wave height are investigated using the global reanalysis ERA-Interim over the period 1979–2012, based on monthly-mean and monthly-maximum data. Besides the traditional reanalysis, the authors include trends obtained at different forecast range, available up to 10 days ahead. Any model biases that are corrected differently over time are likely to introduce spurious trends of variable magnitude. However, at increased forecast range the model tends to relax, being less affected by assimilation. Still, there is a trade-off between removing the impact of data assimilation at longer forecast range and getting a lower level of uncertainty in the predictions at shorter forecast range. Because of the sheer amount of assimilations made in ERA-Interim, directly and indirectly affecting the data, it is difficult, if not impossible, to distinguish effects imposed by all updates. Here, special emphasis is put on the introduction of wave altimeter data in August 1991, ...

83 citations


Journal ArticleDOI
TL;DR: In this article, the impact of a rigid horizontal plate onto a wave crest and, in the limit, onto a flat water surface was investigated using a two-phase incompressible-compressible smoothed particle hydrodynamics (SPH) method.

79 citations


Journal ArticleDOI
TL;DR: In this paper, a 3D-survey at Narrabeen-Collaroy Beach (SE Australia) was used to quantify the control of alongshore nonuniform wave exposure and cross-shore processes on embayed beach rotation.
Abstract: Although embayed beach rotation has been viewed and modeled as an alongshore sediment transport process acting on a uniform beach profile, recent research suggests a more complex response whereby alongshore variability in cross-shore sediment fluxes may be more significant. This study utilizes 5 years of fully three-dimensional beach surveys at Narrabeen-Collaroy Beach (SE Australia) to quantify the control of alongshore nonuniform wave exposure and cross-shore processes on embayed beach rotation. Empirical orthogonal function analysis of the alongshore variability in subaerial beach volume/width and berm slope confirms that the dominant mode of subaerial beach variability is an onshore/offshore sediment exchange that is strongly controlled (R > 0.8) by the alongshore gradient in breaker wave height and coincides with a uniform flattening/steepening of the berm slope. A secondary rotation-like signal is observed in both the subaerial beach volume/width data and, significantly, the berm slope. This inverse flattening/steepening of the berm slope between beach extremities is most likely a proxy for differing cross-shore processes within the surf zone between the exposed and sheltered ends of the embayment, particularly with regards to dissipation of storm wave energy by offshore sandbars and beach recovery following storms. Analysis of the corresponding wave data reveals two distinct time scales of wave forcing characteristic of short-term erosion and longer-term recovery processes. A new conceptual model is presented of three differing modes of embayed beach rotation, with the newly identified beach rotation mode controlled by offshore sandbars considered of particular importance at embayments where headland sheltering of oblique waves is pronounced.

77 citations


Journal ArticleDOI
TL;DR: In this paper, the authors focused on the long-term wind and wave in the central Bay of Bengal from 1979 to 2012 based on the ECMWF ERA-Interim reanalysis data sets and observed statistically declining trends in the mean and extreme wind speed with increasing trend in extreme significant wave height (SWH).
Abstract: The Arabian Sea and Bay of Bengal regions are special interested sea areas in the Northern Hemisphere with large seasonal variability. Present study focused on the long-term wind and wave in the central Bay of Bengal from 1979 to 2012 based on the ECMWF ERA-Interim reanalysis data sets. Data were validated with the nearest available buoy data for the years 2003, 2004 and 2005, and good correlation was observed (root mean square error ≈ 0.17-0.43 m). A clear seasonality was noted with intensified wind and waves during the southwest monsoon season. We observed statistically declining trends in the mean and extreme wind speed (90 th percentile) with increasing trend in extreme significant wave height (SWH). Seasonal analysis also investigated and found that the stronger events/winds during the SW monsoon season are weakening. Conflicting trends in the wind and wave height were mainly due to the swell dominance at the region which was identified by the separate trend analysis of wind-sea and swell height. The area average analysis is carried out to investigate the sensitivity of the identified trend results for the point location and found similar trends for extreme wind speed and SWH. The high (> 5 m) annual maximum SWH in the study area was attributed to the influence of tropical cyclones in the Bay of Bengal, and all of these high waves occurred before 1996 indicating that the influence of tropical cyclones in the study area decreased after 1996.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the surface gravity wave interaction with submerged horizontal flexible porous plate under the assumption of small amplitude water wave theory and structural response was studied by analyzing the complex dispersion relation using contour plots.

71 citations


Journal ArticleDOI
TL;DR: In this paper, the variations in wave power at 19 locations covering the Indian shelf seas using the ERA-Interim dataset produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) are compared with the measured wave parameters in the Arabian Sea and the Bay of Bengal.

69 citations


Journal ArticleDOI
TL;DR: This paper shows that SVR can be successfully trained from simulation-based data, and shows the performance of the SVR in simulation data and how SVR outperforms alternative algorithms such as neural networks.

66 citations


Journal ArticleDOI
TL;DR: In this article, a fault model with a Tohoku-type earthquake fault zone having a random slip distribution was created and a stochastic tsunami hazard analysis using a logic tree was performed.
Abstract: We created a fault model with a Tohoku-type earthquake fault zone having a random slip distribution and performed stochastic tsunami hazard analysis using a logic tree. When the stochastic tsunami hazard analysis results and the Tohoku earthquake observation results were compared, the observation results of a GPS wave gauge off the southern Iwate coast indicated a return period equivalent to approximately 1,709 years (0.50 fractile), and the observation results of a GPS wave gauge off the shore of Fukushima Prefecture indicated a return period of 600 years (0.50 fractile). Analysis of the influence of the number of slip distribution patterns on the results of the stochastic tsunami hazard analysis showed that the number of slip distribution patterns considered greatly influenced the results of the hazard analysis for a relatively large wave height. When the 90 % confidence interval and coefficient of variation of tsunami wave height were defined as an index for projecting the uncertainty of tsunami wave height, the 90 % confidence interval was typically high in locations where the wave height of each fractile point was high. At a location offshore of the Boso Peninsula of Chiba Prefecture where the coefficient of variation reached the maximum, it was confirmed that variations in maximum wave height due to differences in slip distribution of the fault zone contributed to the coefficient of variation being large.

Journal ArticleDOI
TL;DR: In this article, a nonlinear model for the flow of an incompressible and inviscid fluid given in Part I, the wave-induced loads on the submerged, fixed (and rigid) plate are calculated, and results are compared with the available laboratory data, and with linear solutions of the problem.

Journal ArticleDOI
TL;DR: In this paper, a volume of fluid method for coastal structures under the influence of normal incident irregular wave fields is proposed and validated against a multiple of experimental data sets for two dimensional coastal problems.

Journal ArticleDOI
01 May 2015-Energy
TL;DR: In this article, the authors investigated the optimum layout for the co-located wind-wave farm with a view to maximising the benefits of combining wave and offshore wind energy.

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the synergy between wave and wind energy through the comparison of four case studies, and investigated how this synergy can be materialised under different conditions in terms of: (i) location (depth and distance from the coast), (ii) sea climate, and (iii) wind farm layout.

Journal ArticleDOI
TL;DR: In this paper, the influence of the inlet configuration on wave resonance in the gap between two side-by-side fixed bodies is investigated numerically in a 2D numerical wave flume.

Journal ArticleDOI
TL;DR: In this article, a field study was undertaken to investigate the changes of the current speed, wave parameters and sediment resuspension under different wind speeds in the Taihu Lake, where the Acoustic Doppler Current Profiler (ADCP) and MIDAS DWR Wave Recorder were used to collect the data of currents and waves, respectively.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the effect of wind-following or cross-wind seas on the surface momentum exchange during near-neutral atmospheric conditions and found that the magnitude of the cospectral maximum is linearly related to the square of the orbital motion.
Abstract: Atmospheric and surface wave data from several oceanic experiments carried out on the Floating Instrument Platform (FLIP) and the Air–Sea Interaction Spar (ASIS) have been analyzed with the purpose of identifying swell-related effects on the surface momentum exchange during near-neutral atmospheric conditions and wind-following or crosswind seas. All data have a pronounced negative maximum in uw cospectra centered at the frequency of the dominant swell np, meaning a positive contribution to the stress. A similar contribution at this frequency is also obtained for the corresponding crosswind cospectrum. The magnitude of the cospectral maximum is shown to be linearly related to the square of the orbital motion, being equal to , where Hsd is the swell-significant wave height, the effect tentatively being due to strong correlation between the surface component of the orbital motion and the pattern of capillary waves over long swell waves.A model for prediction of the friction velocity from measurement...

Journal ArticleDOI
TL;DR: In this article, an empirical equation based on observed tidal water level and offshore wave height was produced to estimate extreme water levels over the whole period of dune morphological change monitoring, and a good correlation between this empirical equation (1.01Hmoξo) and field runup measurements (Rmax) was obtained (R2 85%).
Abstract: Monitoring of dune erosion and accretion on the high-energy macrotidal Vougot beach in North Brittany (France) over the past decade (2004-2014) has revealed significant morphological changes. Dune toe erosion/accretion records have been compared with extreme water level measurements, defined as the sum of (i) astronomic tide, (ii) storm surge, and (iii) vertical wave runup. Runup parameterization was conducted using swash limits, beach profiles, and hydrodynamic (Hm0, Tm0,-1, and high tide water level – HTWL) data sets obtained from high frequency field surveys. The aim was to quantify in-situ environmental conditions and dimensional swash parameters for the best calibration of Battjes [1] runup formula. In addition, an empirical equation based on observed tidal water level and offshore wave height was produced to estimate extreme water levels over the whole period of dune morphological change monitoring. A good correlation between this empirical equation (1.01Hmoξo) and field runup measurements (Rmax) was obtained (R2 85%). The goodness of fit given by the RMSE was about 0.29 m. A good relationship was noticed between dune erosion and high water levels when the water levels exceeded the dune foot elevation. In contrast, when extreme water levels were below the height of the toe of the dune sediment budget increased, inducing foredune recovery. These erosion and accretion phases may be related to the North Atlantic Oscillation Index.

Journal ArticleDOI
TL;DR: In this paper, an experimental model of transmission of ocean waves by an ice floe is presented, where thin plastic plates with different material properties and thicknesses are used to model the floe.

Journal ArticleDOI
TL;DR: The results obtained are promising, showing an acceptable reconstruction by ordinal methods with respect to nominal ones in terms of wave height and energy flux, in a problem of wave energy range prediction using meteorological variables from numerical models.

Journal ArticleDOI
TL;DR: In this paper, measured wave data from six shallow-water locations in the data-sparse north Indian Ocean are used to assess the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis [ERA-Interim (ERA-I)] wave height and period data in the nearshore waters around India.
Abstract: Bulk wave parameters, such as wave height and wave period, are required for engineering and environmental applications. In this study, measured wave data from six shallow-water locations in the data-sparse north Indian Ocean are used to assess the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis [ERA-Interim (ERA-I)] wave height and period data in the nearshore waters around India. The difference between the ERA-I significant wave height (SWH) and the buoy SWH varies from −1 to 1 m with an average value of −0.1 m for the three west coast locations. For the three east coast locations, the variation ranges from −2.2 to 1.7 m with an average value of −0.2 m. The ERA-I SWH data show positive biases, indicating an overall overestimation for all locations except for the northern location in the west coast of India, where underestimation is observed. During the tropical cyclone period, a large (~33%) underestimation of SWH in the ERA-I data is observed. Hence, the ERA-I SWH ...

Journal ArticleDOI
TL;DR: In this article, changes in the magnitude, duration, frequency and approach direction of the Atlantic storms over the Gulf of Cadiz (SW Iberian Peninsula) were identified by computing various storm characteristics such as maximum wave height, total energy per storm wave direction and storm duration.
Abstract: In the context of increased coastal hazards due to variability in storminess patterns, the danger of coastal damages and/or morphological changes is related to the sum of sea level conditions, storm surge, maximum wave height and run up values. In order to better understand the physical processes that cause the variability of the above parameters a 44 years reanalysis record (HIPOCAS) was used. The HIPOCAS time-series was validated with real wave and sea-level data using linear and vector correlation methods. In the present work changes in the magnitude, duration, frequency and approach direction of the Atlantic storms over the Gulf of Cadiz (SW Iberian Peninsula) were identified by computing various storm characteristics such as maximum wave height, total energy per storm wave direction and storm duration. The obtained time-series were compared with large-scale atmospheric indices such as the North Atlantic Oscillation (NAO) and the East Atlantic pattern. The results show a good correlation between negative NAO values and increased storminess over the entire Gulf of Cadiz. Furthermore, negative NAO values were correlated with high residual sea level values. Finally, a joint probability analysis of storm and sea level analysis resulted in increased probabilities of the two events happening at the same time indicating higher vulnerability of the coast and increased coastal risks. The above results were compared with coastal inundation events that took place over the last winter seasons in the province of Cadiz.

Journal ArticleDOI
TL;DR: A nonstationary model based on a time-dependent version of the Generalized Pareto Distribution (GPD)-Poisson point process model has been implemented and applied to model extreme wave heights in the Mediterranean basin this paper.
Abstract: A nonstationary model based on a time-dependent version of the Generalized Pareto Distribution (GPD)-Poisson point process model has been implemented and applied to model extreme wave heights in the Mediterranean basin. Thirty-two years of wave hindcast data have been provided by a forecast/hindcast numerical chain model operational at the University of Genoa (www.dicca.unige.it/meteocean). The nonstationary behavior of wave height maxima prompted the modeling of GEV parameters with harmonic functions. Harmonics have been introduced to model seasonal cycles within a year, also taking into account long-term trend and covariates effects. The model has been applied on eight locations corresponding to buoys belonging to the RON (Rete Ondametrica Nazionale), chosen in order to represent best the main features and variability of waves along the Italian coast. The best performing model is chosen among a large set of possible candidates identified by different combinations of wave heights maxima and model parameters. Direct comparison with stationary results has been performed; furthermore, the model has demonstrated a good performance in gathering different seasonal behaviors related to the main meteorological forcing standing on the Mediterranean Sea. Trends related to extreme significant wave heights have also been evaluated in order to offer some insight into decadal-scale wave climate. Results achieved show how the use of a nonstationary statistical model together with the analysis of the main meteorological forcings characterizing the area could prove useful in understanding wave climate related to atmospheric dynamics.

Journal ArticleDOI
TL;DR: In this paper, the authors estimate the future changes in mean wave climate and the sensitivity of the wave climate to sea surface temperature (SST) conditions in an effort to understand the mechanism behind wave climate changes by specifically looking at spatial SST variation.
Abstract: Changes in ocean surface waves elicit a variety of impacts on coastal environments. To assess the future changes in the ocean surface wave climate, several future projections of global wave climate have been simulated in previous studies. However, previously there has been little discussion about the causes behind changes in the future wave climate and the differences between projections. The objective of this study is to estimate the future changes in mean wave climate and the sensitivity of the wave climate to sea surface temperature (SST) conditions in an effort to understand the mechanism behind the wave climate changes by specifically looking at spatial SST variation. A series of wave climate projections forced by surface winds from the MRI-AGCM3.2 were conducted based on SST ensemble experiments. The results yield future changes in annual mean wave height that are within about ±0.3 m. The future changes in summertime wave height in the western North Pacific (WNP), which are influenced by tro...

Journal ArticleDOI
TL;DR: In this paper, an alternative multivariate method for assessing extreme storm conditions is proposed based on the Nataf model and the Inverse First Order Reliability Method (IFORM) and uses measurements or hindcasts of wind speed, wave height and peak spectral period to estimate an environmental surface which defines combinations of these parameters with a particular recurrence period.

Journal ArticleDOI
TL;DR: In this paper, the authors presented numerical simulations using the HAWC2 code to study an offshore wind turbine in parked conditions, and the results from the simulations will be compared with the processed data obtained from real measurements.
Abstract: Offshore wind turbines are complex structures, and their dynamics can vary significantly because of changes in operating conditions, e.g., rotor-speed, pitch angle or changes in the ambient conditions, e.g., wind speed, wave height or wave period. Especially in parked conditions, with reduced aerodynamic damping forces, the response due to wave actions with wave frequencies close to the first structural resonance frequencies can be high. Therefore, this paper will present numerical simulations using the HAWC2 code to study an offshore wind turbine in parked conditions. The model has been created according to best practice and current standards based on the design of an existing Vestas V90 offshore wind turbine on a monopile foundation in the Belgian North Sea. The damping value of the model's first fore-aft mode has been tuned on the basis of measurements obtained from a long-term ambient monitoring campaign on the same wind turbine. Using the updated model of the offshore wind turbine, the paper will present some of the effects of the different design parameters and the different ambient conditions on the dynamics of an offshore wind turbine. The results from the simulations will be compared with the processed data obtained from the real measurements. The accuracy of the model will be discussed in terms of resonance frequencies, mode shapes, damping value and acceleration levels, and the limitations of the simulations in modeling of an offshore wind turbine will be addressed. Copyright © 2014 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, the effect of climate change on wave energy in the Persian Gulf is investigated, and the results of these two 30-yearly wave modelings using SWAN model showed that the average wave power changes slightly in the future.
Abstract: Excessive usage of fossil fuels and high emission of greenhouse gases have increased the earth’s temperature, and consequently have changed the patterns of natural phenomena such as wind speed, wave height, etc. Renewable energy resources are ideal alternatives to reduce the negative effects of increasing greenhouse gases emission and climate change. However, these energy sources are also sensitive to changing climate. In this study, the effect of climate change on wave energy in the Persian Gulf is investigated. For this purpose, future wind data obtained from CGCM3.1 model were downscaled using a hybrid approach and modification factors were computed based on local wind data (ECMWF) and applied to control and future CGCM3.1 wind data. Downscaled wind data was used to generate the wave characteristics in the future based on A2, B1, and A1B scenarios, while ECMWF wind field was used to generate the wave characteristics in the control period. The results of these two 30-yearly wave modelings using SWAN model showed that the average wave power changes slightly in the future. Assessment of wave power spatial distribution showed that the reduction of the average wave power is more in the middle parts of the Persian Gulf. Investigation of wave power distribution in two coastal stations (Boushehr and Assalouyeh ports) indicated that the annual wave energy will decrease in both stations while the wave power distribution for different intervals of significant wave height and peak period will also change in Assalouyeh according to all scenarios.

Journal ArticleDOI
TL;DR: In this article, a Computational Fluid Dynamics (CFD) model based on immersed boundary method, in combination with a two-body structural model of TLPWT is developed to study wave induced responses of TTLWT in deep water.

Journal ArticleDOI
TL;DR: In this article, a numerical wave model was used for hindcasting of wave conditions around the United Kingdom, in particular for Scottish waters, for the purpose of wave energy resource assessment at potential device development sites.