Discussion of “Extreme Wave Height Distributions over Oceans”

1974 ◽  
Vol 100 (2) ◽  
pp. 163-164
Author(s):  
Subrata K. Chakrabarti
Keyword(s):  
Wave Height ◽  
Extreme Wave

scholarly journals Assessment of reliability of extreme wave height prediction models

2017 ◽  
Vol 17 (3) ◽  
pp. 409-421 ◽  
Author(s):  
Satish Samayam ◽  
Valentina Laface ◽  
Sannasiraj Sannasi Annamalaisamy ◽  
Felice Arena ◽  
Sundar Vallam ◽  
...  
Keyword(s):  
North America ◽  
Mediterranean Sea ◽  
Wave Height ◽  
Prediction Models ◽  
North Pacific Ocean ◽  
Coastal Hazards ◽  
Extreme Wave ◽  
Indian Water ◽  
Wave Hindcast ◽  
Buoy Data

Abstract. Extreme waves influence coastal engineering activities and have an immense geophysical implication. Therefore, their study, observation and extreme wave prediction are decisive for planning of mitigation measures against natural coastal hazards, ship routing, design of coastal and offshore structures. In this study, the estimates of design wave heights associated with return period of 30 and 100 years are dealt with in detail. The design wave height is estimated based on four different models to obtain a general and reliable model. Different locations are considered to perform the analysis: four sites in Indian waters (two each in Bay of Bengal and the Arabian Sea), one in the Mediterranean Sea and two in North America (one each in North Pacific Ocean and the Gulf of Maine). For the Indian water domain, European Centre for Medium-Range Weather Forecasts (ECMWF) global atmospheric reanalysis ERA-Interim wave hindcast data covering a period of 36 years have been utilized for this purpose. For the locations in Mediterranean Sea and North America, both ERA-Interim wave hindcast and buoy data are considered. The reasons for the variation in return value estimates of the ERA-Interim data and the buoy data using different estimation models are assessed in detail.

scholarly journals Wind and Current Effects on Extreme Wave Formation and Breaking

2017 ◽  
Vol 47 (7) ◽  
pp. 1817-1841 ◽  
Author(s):  
Qingping Zou ◽  
Haifei Chen
Keyword(s):  
Wave Height ◽  
Wind Forcing ◽  
Vertical Shear ◽  
Breaking Wave ◽  
Wave Group ◽  
Extreme Wave ◽  
Two Phase ◽  
Wind Actions ◽  
Secondary Vortices ◽  
Focus Point

AbstractWind and current effects on the evolution of a two-dimensional dispersive focusing wave group are investigated using a two-phase flow model. A Navier–Stokes solver is combined with the Smagorinsky subgrid-scale stress model and volume of fluid (VOF) air–water interface capturing scheme. Model predictions compare well with the experimental data with and without wind. It was found that the following and opposing winds shift the focus point downstream and upstream, respectively. The shift of focus point is mainly due to the action of wind-driven current instead of direct wind forcing. Under strong following/opposing wind forcing, there appears a slight increase/decrease of the extreme wave height at the focus point and an asymmetric/symmetric behavior in the wave focusing and defocusing processes. Under a weak following wind, however, the extreme wave height decreases with increasing wind speed because of the dominant effect of the wind-driven current over direct wind forcing. The vertical shear of the wind-driven current plays an important role in determining the location of and the extreme wave height at the focus point under wind actions. Furthermore, it was found that the thin surface layer current is a better representation of the wind-driven current for its role in wind influences on waves than the depth-uniform current used by previous studies. Airflow structure above a breaking wave group and its link to the energy flux from wind to wave as well as wind influence on breaking are also examined. The flow structure in the presence of a following wind is similar to that over a backward-facing step, while that in the presence of an opposing wind is similar to that over an airfoil at high angles of attack. Both primary and secondary vortices are observed over the breaking wave with and without wind of either direction. Airflow separates over the steep crest and causes a pressure drop in the lee of the crest. The resulting form drag may directly affect the extreme wave height. The wave breaking location and intensity are modified by the following and opposing wind in a different fashion.

Uncertainties in Extreme Wave Height Estimates for Hurricane-Dominated Regions

2007 ◽  
Vol 129 (4) ◽  
pp. 300-305 ◽  
Author(s):  
Philip Jonathan ◽  
Kevin Ewans
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Small Data ◽  
Extreme Wave ◽  
Significant Wave ◽  
Wave Characteristics ◽  
Height Estimates ◽  
Wave Heights ◽  
Using Data ◽  
High Percentile

Inherent uncertainties in estimation of extreme wave heights in hurricane-dominated regions are explored using data from the GOMOS Gulf of Mexico hindcast for 1900–2005. In particular, the effect of combining correlated values from a neighborhood of 72 grid locations on extreme wave height estimation is quantified. We show that, based on small data samples, extreme wave heights are underestimated and site averaging usually improves estimates. We present a bootstrapping approach to evaluate uncertainty in extreme wave height estimates. We also argue in favor of modeling supplementary indicators for extreme wave characteristics, such as a high percentile (95%) of the distribution of 100-year significant wave height, in addition to its most probable value, especially for environments where the distribution of 100-year significant wave height is strongly skewed.

scholarly journals Evolution of a Random Directional Wave and Freak Wave Occurrence

2009 ◽  
Vol 39 (3) ◽  
pp. 621-639 ◽  
Author(s):  
Takuji Waseda ◽  
Takeshi Kinoshita ◽  
Hitoshi Tamura
Keyword(s):  
Wave Height ◽  
Wave Interaction ◽  
Northwest Pacific ◽  
Frequency Bandwidth ◽  
Extreme Wave ◽  
Spectral Parameters ◽  
Freak Wave ◽  
Resonant Wave ◽  
Directional Wave ◽  
Wind Sea

Abstract The evolution of a random directional wave in deep water was studied in a laboratory wave tank (50 m long, 10 m wide, 5 m deep) utilizing a directional wave generator. A number of experiments were conducted, changing the various spectral parameters (wave steepness 0.05 < ɛ < 0.11, with directional spreading up to 36° and frequency bandwidth 0.2 < δk/k < 0.6). The wave evolution was studied by an array of wave wires distributed down the tank. As the spectral parameters were altered, the wave height statistics change. Without any wave directionality, the occurrence of waves exceeding twice the significant wave height (the freak wave) increases as the frequency bandwidth narrows and steepness increases, due to quasi-resonant wave–wave interaction. However, the probability of an extreme wave rapidly reduces as the directional bandwidth broadens. The effective Benjamin–Feir index (BFIeff) is introduced, extending the BFI (the relative magnitude of nonlinearity and dispersion) to incorporate the effect of directionality, and successfully parameterizes the observed occurrence of freak waves in the tank. Analysis of the high-resolution hindcast wave field of the northwest Pacific reveals that such a directionally confined wind sea with high extreme wave probability is rare and corresponds mostly to a swell–wind sea mixed condition. Therefore, extreme wave occurrence in the sea as a result of quasi-resonant wave–wave interaction is a rare event that occurs only when the wind sea directionality is extremely narrow.

The Equivalent Power Storm Model for Long-Term Predictions of Extreme Wave Events

2009 ◽  
Author(s):  
Francesco Fedele ◽  
Felice Arena
Keyword(s):  
Wave Height ◽  
Return Period ◽  
Shape Parameter ◽  
Extreme Wave ◽  
Maximum Wave Height ◽  
Wave Measurements ◽  
Sea Storm ◽  
Storm Model ◽  
Good Agreement

We present the Equivalent Power Storm (EPS) model as a generalization of the Equivalent Triangular Storm (ETS) model of Boccotti for the long-term statistics of extreme wave events. In the EPS model, each actual storm is modeled in time t by a power law ∼|t−t0|λ, where λ is a shape parameter and t0 is the time when the storm peak occurs. We then derive the general expression of the return period R(Hs > h) of a sea storm in which the maximum significant wave height Hs exceeds a fixed threshold h as function of λ. Further, given the largest wave height Hmax, we identify the most probable storm in which the largest wave occurs and derive an explicit expression for the return period R(Hmax >H) of a storm in which the maximum wave height exceeds a given threshold H. Finally, we analyze wave measurements retrieved from two of the NOAA-NODC buoys in the Atlantic and Pacific oceans and find that the EPS predictions are in good agreement with those from the ETS model.

Systematically Varied Rogue Wave Sequences for the Experimental Investigation of Extreme Structure Behavior

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Günther F. Clauss ◽  
Christian E. Schmittner ◽  
Janou Hennig
Keyword(s):  
Wave Height ◽  
Rogue Wave ◽  
Wave Train ◽  
Weather Conditions ◽  
Offshore Structures ◽  
Severe Weather ◽  
Wave Profile ◽  
Bending Moments ◽  
Extreme Wave ◽  
Improved Design

For an improved design of ships and offshore structures with regard to their behavior under severe weather conditions, wave height and steepness as well as the shape of the wave profile have to be considered. In this paper, the extreme new year wave as documented in numerous publications is varied with respect to wave height and period. These varied wave sequences are realized and measured in a model tank and applied to the investigation of motions and bending moments of a floating production storage and offloading ship. The results are compared to the responses in the original wave train. An investigation of the riskiness of extreme wave sequences in comparison with existing rules concludes this paper.

scholarly journals Projected 21st Century changes in extreme wind-wave events

2020 ◽  
Author(s):  
Alberto Meucci
Keyword(s):  
Wave Height ◽  
21St Century ◽  
Wind Wave ◽  
Ocean Waves ◽  
Extreme Value Analysis ◽  
High Latitudes ◽  
Extreme Wave ◽  
Value Analysis ◽  
The North ◽  
Uncertainty Estimates

<p>Extreme ocean waves shape world coastlines and significantly impact offshore operations. Climate change may further exacerbate these effects increasing losses in human lives and economic activities. Studies generally agree on the trends in the mean values, yet there is no consensus on the extreme events, and whether their magnitude and/or frequency are changing. The present work applies an innovative extreme value analysis approach to a multi-model ensemble wind-wave climate dataset, derived from seven global climate models, to evaluate projected extreme wave height changes towards the end of the 21st century. Under two greenhouse gas emission scenarios, we find that at the end of the 21st century, the one in 100-year wave height event increases across the scenarios by 5 to 15 % over the Southern Ocean. The North Atlantic shows a decrease at low to mid-latitudes (5 to 15 %) and an increase at the high latitudes (10 %). The extreme wave heights in the North Pacific increase at the high latitudes by 5 to 10 %. The present work suggests that pooling an ensemble of future projected ocean storms from different GCMs might significantly improve uncertainty estimates connected to future coastal and offshore wave extremes, thereby improving climate adaptation strategies.</p>

A climatology of extreme wave height events impacting eastern Lake Ontario shorelines

2018 ◽  
Vol 136 (1-2) ◽  
pp. 543-552 ◽  
Author(s):  
Matthew B. Grieco ◽  
Arthur T. DeGaetano
Keyword(s):  
Wave Height ◽  
Lake Ontario ◽  
Extreme Wave

scholarly journals Evaluation of extreme wave probability on the basis of long-term data analysis

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 1321-1327 ◽  
Author(s):  
Kirill Bulgakov ◽  
Vadim Kuzmin ◽  
Dmitry Shilov
Keyword(s):  
Wave Height ◽  
Wind Wave ◽  
Cumulative Probability ◽  
Extreme Waves ◽  
Model Data ◽  
Extreme Wave ◽  
Method Of Calculation ◽  
Wave Heights ◽  
Term Data

Abstract. A method of calculation of wind wave height probability based on the significant wave height probability is described (Chalikov and Bulgakov, 2017). The method can also be used for estimation of the height of extreme waves of any given cumulative probability. The application of the method on the basis of long-term model data is presented. Examples of averaged annual and seasonal fields of extreme wave heights obtained using the above method are given. Areas where extreme waves can appear are shown.

Sign in / Sign up

Export Citation Format

Share Document