scholarly journals A PARAMETRIC HURRICANE WAVE PREDICTION MODEL

1988 ◽  
Vol 1 (21) ◽  
pp. 82
Author(s):  
Ian R. Young
Keyword(s):  
Spatial Distribution ◽  
Radiative Transfer Equation ◽  
Synthetic Data ◽  
Wave Model ◽  
Limited Growth ◽  
Forward Movement ◽  
Spectral Wave Model ◽  
Wave Conditions ◽  
Two Parameters ◽  
The Waves

A spectral wave model based on a numerical solution of the Radiative Transfer Equation is used to create a synthetic data base on wave conditions within hurricanes. The results indicate that both the velocity of forward movement and maximum wind velocity within the storm play an important role in determining both the magnitude of the waves generated and also the spatial distribution of these waves. An equivalent fetch for hurricane wave generation which is a function of these two parameters is proposed. This concept, together with the standard JONSWAP fetch limited growth relationships, provide a simple means for estimating wave conditions within hurricanes.

scholarly journals Wave Directions in a Narrow Bay

2010 ◽  
Vol 40 (1) ◽  
pp. 155-169 ◽  
Author(s):  
Heidi Pettersson ◽  
Kimmo K. Kahma ◽  
Laura Tuomi
Keyword(s):  
Wave Model ◽  
Wave Climate ◽  
Spectral Peak ◽  
Step Size ◽  
Weakly Nonlinear ◽  
Spectral Wave Model ◽  
Directional Coupling ◽  
Directional Wave ◽  
The Baltic ◽  
The Waves

Abstract In slanting fetch conditions the direction of actively growing waves is strongly controlled by the fetch geometry. The effect was found to be pronounced in the long and narrow Gulf of Finland in the Baltic Sea, where it significantly modifies the directional wave climate. Three models with different assumptions on the directional coupling between the wave components were used to analyze the physics responsible for the directional behavior of the waves in the gulf. The directionally decoupled model produced the direction at the spectral peak correctly when the slanting fetch geometry was narrow but gave a weaker steering than observed when the fetch geometry was broader. The method of Donelan estimated well the direction at the spectral peak in well-defined slanting fetch conditions, but overestimated the longer fetch components during wave growth from a more complex shoreline. Neither the decoupled nor the Donelan model reproduced the observed shifting of direction with the frequency. The performance of the third-generation spectral wave model (WAM) in estimating the wave directions was strongly dependent on the grid resolution of the model. The dominant wave directions were estimated satisfactorily when the grid-step size was dropped to 5 km in the gulf, which is 70 km in its narrowest part. A mechanism based on the weakly nonlinear interactions is proposed to explain the strong steering effect in slanting fetch conditions.

Generation of Multivariate Wave Conditions as Input for a Probabilistic Level III Breakwater Design

2014 ◽  
Author(s):  
Peter Mercelis ◽  
Marc Dufour ◽  
Ariel Alvarez Gebelin ◽  
Vincent Gruwez ◽  
Sarah Doorme ◽  
...  
Keyword(s):  
Water Level ◽  
Wind Velocity ◽  
Regression Function ◽  
Wave Model ◽  
Water Levels ◽  
Spectral Wave Model ◽  
Navigation Channel ◽  
Extreme Wind ◽  
Wave Conditions ◽  
Area Of Concern

For an offshore LNG project situated in the estuary of the Rio de la Plata nearby Montevideo, Uruguay, it was required to verify the deterministic design of the protective rubble mound breakwater and the jetty infrastructure with a level three probabilistic design. Therefore, in first instance extreme site conditions were required both in front of and behind the breakwater. To obtain these conditions, the first step is to extrapolate the offshore variables in order to translate them to the breakwater location. All the possible combinations of extreme wind, water level and waves are quantified with a probability of occurrence. A combination of univariate extreme value distributions, copula’s and regression is used to describe the multivariate statistical behaviour of the offshore variables. The main variable is the wind velocity, as in the area of concern extreme wave conditions are wind driven. The secondary variable is water level. Wind velocity and water levels are only correlated for some wind directions. For these directions, wind velocity and water level extreme value distributions are linked through a multivariate Gumbel Copula. The wave height at the model boundaries was taken into account by a regression function with the extreme wind velocity at the offshore location and the wave period by a regression function with the wave height. This way 1515 synthetic events were selected and simulated with the spectral wave model SWAN, each of which a frequency of occurrence is calculated for. However, due to refraction and diffraction effects of the approach channel (in the area of concern water depths are limited to about 7 m and the navigation channel has a depth of about 14 m), the port basin and the breakwater itself, the spectral wave model SWAN is not sufficient to accurately calculate the local wave conditions in the entire area of interest. Therefore a non-linear Boussinesq wave model (i.e. Mike 21 BW) was set up in addition, using input from the spectral model at the boundary and including the navigation channel of more than 12 km long. Combining both models, significant wave heights are obtained on both the seaward side and the leeside of the breakwater with corresponding frequencies of occurrence. This approach allows the determination of conditional return periods and generates the site conditions required for a probabilistic level three design of the breakwater and the jetty infrastructure taking for example the joint probabilities between waves and water levels fully into account as needed for overtopping or failure calculations.

Numerical simulation of wave conditions in nearshore island area for sea-crossing bridge using spectral wave model

2017 ◽  
Vol 21 (5) ◽  
pp. 756-768 ◽  
Author(s):  
Zilong Ti ◽  
Kai Wei ◽  
Shunquan Qin ◽  
Yongle Li ◽  
Dapeng Mei
Keyword(s):  
Numerical Simulation ◽  
Spatial Pattern ◽  
Wave Model ◽  
High Energy ◽  
Engineering Practice ◽  
Breaking Wave ◽  
Bridge Site ◽  
Island Area ◽  
Spectral Wave Model ◽  
Wave Conditions

The assessment of wave conditions is a primary task for the design, construction, and structural analysis of sea-crossing bridge. This article presents a numerical simulation and a field measurement to study the wave conditions in the nearshore island area for sea-crossing bridges. Pingtan Strait sea-crossing bridge site was selected as an example of nearshore island area. A 3-day high-energy wave event was measured and simulated using spectral wave model. The parameters of the numerical model were calibrated through the comparison with the field measured wave data. The spatial pattern of wave conditions along the bridge and the wave-breaking zone were analyzed based on the calibrated model. The analytical procedures suggested in the Chinese Code for nearshore wave prediction were finally testified through the comparison with numerical results. The research showed that (1) spectral wave model predicts the wave conditions in bridge site reasonably; (2) seabed terrain and islands significantly influence wave conditions, wave spatial pattern, and breaking wave zones; and (3) analytical wave simulation procedure recommended in the Code is not suitable to island area for sea-crossing bridge. This research allows a better understanding of wave conditions for sea-crossing bridge site and could provide useful reference for engineering practice.

scholarly journals Characteristics and dynamics of crescentic bar events at an open, Mediterranean beach

2020 ◽  
Author(s):  
Rinse de Swart ◽  
Francesca Ribas ◽  
Daniel Calvete ◽  
Gonzalo Simarro ◽  
Jorge Guillén
Keyword(s):  
Visual Analysis ◽  
Wave Model ◽  
Wave Direction ◽  
Geophysical Research ◽  
Spectral Wave Model ◽  
First Results ◽  
Strong Relation ◽  
Wave Conditions ◽  
Using Data ◽  
Bar Formation

<p>Crescentic sand bars have attracted significant attention from coastal scientists during the last decades, which has lead to comparatively good understanding of their formation mechanism, as well as their characteristics and dynamics (e.g. Van Enckevort et al., 2004; Price and Ruessink, 2011). However, the effect of wave obliquity on crescentic bar formation is not yet clear, and processes like coupling of crescentic bars with megacusps deserve further attention. Furthermore, the mechanisms leading to crescentic bar straightening are not well understood. Previously, this was mainly linked to high-energetic wave conditions, but more recent studies (e.g. Price and Ruessink, 2011; Garnier et al., 2013) indicate that this is not always the case. Instead, those studies have found that bar straightening predominantly occurs when the waves are obliquely incident. Finally, there are not many studies of crescentic bars in fetch-limited environments with insignificant tides (such as Mediterranean beaches). Therefore, the objective of the present work is to increase our knowledge on the dynamics of crescentic bars (including bar straightening) using data from an open, Mediterranean beach (Castelldefels beach, 20 km southwest of Barcelona) with hardly any tides and limited fetch.</p><p><span>Crescentic bar dynamics have been analysed using a nearly 8-year dataset of time-exposure video images (October 2010 to August 2018). The crescentic bar events, including formation and destruction moments, have been detected using visual analysis. Wave conditions in front of the study site have been collected by propagating 2D spectra (measured by a permanent wave buoy in front of Barcelona harbour) using the SWAN spectral wave model. The first results indicate that there is a lot of morphodynamic variability at the study site, even for low-energetic wave conditions (</span><span><em>H</em></span><sub><span><em>m0</em></span></sub><span> < 0.5 m). </span>Tens of crescentic bar events, including formation, evolution and destruction, can be observed. <span>The bars show a large variation in wavelength (ranging from 100 to 500 m), which is often related to splitting and merging of individual crescents.</span> <span>Furthermore</span><span>, the results reveal a strong relation between crescentic bar formation and the initial configuration of the bathymetry. Crescentic bars develop often when the sandbar is located some distance from the shoreline, whilst they are hardly observed when the sandbar is located close to the shoreline. </span>Further work (which will be presented at the conference) consists of a detailed analysis of bar characteristics, including their alongshore migration, and the quantification of the role of wave conditions (especially wave direction) on crescentic bar dynamics.</p><p><span>R</span><span>eferences<br></span>Garnier, R., Falqués, A., Calvete, D., Thiebot, J., & Ribas, F. (2013). A mechanism for sandbar straightening by oblique wave incidence. <em>Geophysical Research Letters</em>, <em>40</em>(11), 2726-2730.<br><span>Price, T. D., & Ruessink, B. G. (2011). State dynamics of a double sandbar system. </span><span><em>Continental Shelf Research, 31(6)</em></span><span>, 659-674.<br></span>Van Enckevort, I. M. J., Ruessink, B. G., Coco, G., Suzuki, K., Turner, I. L., Plant, N. G., & Holman, R. A. (2004). Observations of nearshore crescentic sandbars. <em>Journal of Geophysical Research: Oceans</em>, <em>109</em>(C6).</p>

scholarly journals Evaluating the accuracy and uncertainty of atmospheric and wave model hindcasts during severe events using model ensembles

2021 ◽  
Author(s):  
Ali Abdolali ◽  
Andre van der Westhuysen ◽  
Zaizhong Ma ◽  
Avichal Mehra ◽  
Aron Roland ◽  
...  
Keyword(s):  
Extreme Event ◽  
Numerical Models ◽  
Model Performance ◽  
Ground Truth ◽  
Wave Model ◽  
Atmospheric Model ◽  
Stationary Source ◽  
Source Point ◽  
Spectral Wave Model ◽  
Model Ensembles

AbstractVarious uncertainties exist in a hindcast due to the inabilities of numerical models to resolve all the complicated atmosphere-sea interactions, and the lack of certain ground truth observations. Here, a comprehensive analysis of an atmospheric model performance in hindcast mode (Hurricane Weather and Research Forecasting model—HWRF) and its 40 ensembles during severe events is conducted, evaluating the model accuracy and uncertainty for hurricane track parameters, and wind speed collected along satellite altimeter tracks and at stationary source point observations. Subsequently, the downstream spectral wave model WAVEWATCH III is forced by two sets of wind field data, each includes 40 members. The first ones are randomly extracted from original HWRF simulations and the second ones are based on spread of best track parameters. The atmospheric model spread and wave model error along satellite altimeters tracks and at stationary source point observations are estimated. The study on Hurricane Irma reveals that wind and wave observations during this extreme event are within ensemble spreads. While both Models have wide spreads over areas with landmass, maximum uncertainty in the atmospheric model is at hurricane eye in contrast to the wave model.

scholarly journals Coastal Mangrove Response to Marine Erosion: Evaluating the Impacts of Spatial Distribution and Vegetation Growth in Bangkok Bay from 1987 to 2017

2020 ◽  
Vol 12 (2) ◽  
pp. 220 ◽  
Author(s):  
Han Xiao ◽  
Fenzhen Su ◽  
Dongjie Fu ◽  
Qi Wang ◽  
Chong Huang
Keyword(s):  
Spatial Distribution ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Mangrove Ecosystem ◽  
Early Growth ◽  
Growth Stages ◽  
Human Disturbances ◽  
Vegetation Growth ◽  
Two Parameters ◽  
The Impact

Long time-series monitoring of mangroves to marine erosion in the Bay of Bangkok, using Landsat data from 1987 to 2017, shows responses including landward retreat and seaward extension. Quantitative assessment of these responses with respect to spatial distribution and vegetation growth shows differing relationships depending on mangrove growth stage. Using transects perpendicular to the shoreline, we calculated the cross-shore mangrove extent (width) to represent spatial distribution, and the normalized difference vegetation index (NDVI) was used to represent vegetation growth. Correlations were then compared between mangrove seaside changes and the two parameters—mangrove width and NDVI—at yearly and 10-year scales. Both spatial distribution and vegetation growth display positive impacts on mangrove ecosystem stability: At early growth stages, mangrove stability is positively related to spatial distribution, whereas at mature growth the impact of vegetation growth is greater. Thus, we conclude that at early growth stages, planting width and area are more critical for stability, whereas for mature mangroves, management activities should focus on sustaining vegetation health and density. This study provides new rapid insights into monitoring and managing mangroves, based on analyses of parameters from historical satellite-derived information, which succinctly capture the net effect of complex environmental and human disturbances.

scholarly journals Wave power assessment in Faroese waters using an oceanic to nearshore scale spectral wave model

Energy ◽  
2021 ◽  
pp. 121404
Author(s):  
Bárður Joensen ◽  
Bárður A. Niclasen ◽  
Harry B. Bingham
Keyword(s):  
Wave Model ◽  
Wave Power ◽  
Spectral Wave Model

Evaluating the Coupledness of the Aerodynamics and Hydrodynamics on the Estimation of Fatigue Damage Equivalent Load for a Floating Offshore Wind Platform

2018 ◽  
Author(s):  
Samuel Kanner ◽  
Bingbin Yu
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Environmental Conditions ◽  
Offshore Wind ◽  
Coupled Analysis ◽  
Offshore Wind Turbine ◽  
Wave Conditions ◽  
Equivalent Load ◽  
The Waves

In this research, the estimation of the fatigue life of a semi-submersible floating offshore wind platform is considered. In order to accurately estimate the fatigue life of a platform, coupled aerodynamic-hydrodynamic simulations are performed to obtain dynamic stress values. The simulations are performed at a multitude of representative environmental states, or “bins,” which can mimic the conditions the structure may endure at a given site, per ABS Floating Offshore Wind Turbine Installation guidelines. To accurately represent the variety of wind and wave conditions, the number of environmental states can be of the order of 103. Unlike other offshore structures, both the wind and wave conditions must be accounted for, which are generally considered independent parameters, drastically increasing the number of states. The stress timeseries from these simulations can be used to estimate the damage at a particular location on the structure by using commonly accepted methods, such as the rainflow counting algorithm. The damage due to either the winds or the waves can be estimated by using a frequency decomposition of the stress timeseries. In this paper, a similar decoupled approach is used to attempt to recover the damages induced from these coupled simulations. Although it is well-known that a coupled, aero-hydro analysis is necessary in order to accurately simulate the nonlinear rigid-body motions of the platform, it is less clear if the same statement could be made about the fatigue properties of the platform. In one approach, the fatigue damage equivalent load is calculated independently from both scatter diagrams of the waves and a rose diagram of the wind. De-coupled simulations are performed to estimate the response at an all-encompassing range of environmental conditions. A database of responses based on these environmental conditions is constructed. The likelihood of occurrence at a case-study site is used to compare the damage equivalent from the coupled simulations. The OC5 platform in the Borssele wind farm zone is used as a case-study and the damage equivalent load from the de-coupled methods are compared to those from the coupled analysis in order to assess these methodologies.

scholarly journals Predicting Wave‐Induced Sediment Resuspension at the Perimeter of Lakes Using a Steady‐State Spectral Wave Model

2019 ◽  
Vol 55 (2) ◽  
pp. 1279-1295 ◽  
Author(s):  
D. C. Roberts ◽  
P. Moreno‐Casas ◽  
F. A. Bombardelli ◽  
S. J. Hook ◽  
B. R. Hargreaves ◽  
...  
Keyword(s):  
Steady State ◽  
Sediment Resuspension ◽  
Wave Model ◽  
Spectral Wave Model ◽  
Wave Induced
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