The Bivariate Distribution of Wave Heights and Periods in Mixed Sea States

1999 ◽  
Vol 121 (2) ◽  
pp. 102-108 ◽  
Author(s):  
G. Rodri´guez ◽  
C. Guedes Soares
Keyword(s):  
Bivariate Distribution ◽  
Dimensionless Parameters ◽  
Wave Heights ◽  
Probabilistic Structure ◽  
Two Parameters ◽  
Sea Wave

The probabilistic structure of the bivariate distribution of sea wave heights and periods in sea states with two-peaked spectra is examined by means of numerically simulated wave records. Two-peaked sea states are classified in nine representative groups, in terms of two dimensionless parameters. The asymmetric and bimodal nature of the distribution is examined for each one of these two parameters.

scholarly journals Long-term spatial variations in the Baltic Sea wave fields

Ocean Science ◽  
2011 ◽  
Vol 7 (1) ◽  
pp. 141-150 ◽  
Author(s):  
T. Soomere ◽  
A. Räämet
Keyword(s):  
Baltic Sea ◽  
Spatial Variations ◽  
Extreme Wave ◽  
The Baltic Sea ◽  
Wave Fields ◽  
Wave Heights ◽  
The Baltic ◽  
Wave Properties ◽  
Sea Wave

Abstract. This study focuses on spatial patterns in linear trends of numerically reconstructed basic wave properties (average and extreme wave heights, wave periods) in the Baltic Sea under the assumption of no ice cover. Numerical simulations of wave conditions for 1970–2007, using the WAM wave model and adjusted geostrophic winds, revealed extensive spatial variations in long-term changes in both average and extreme wave heights in the Baltic Sea but almost no changes in the basinwide wave activity and wave periods. There has been a statistically significant decrease in the annual mean significant wave height by more than 10% between the islands of Öland and Gotland and in the southward sea area, and a substantial increase to the south-west of Bornholm, near the coast of Latvia, between the Åland Archipelago and the Swedish mainland, and between the Bothnian Sea and the Bothnian Bay. Variations in extreme wave heights (defined as the threshold for 1% of the highest waves each year) show similar patterns of changes. In several areas the trends in average and extreme wave heights are different. Such a complicated pattern of changes indicates that (i) different regions of the Baltic Sea basin have experienced widespread but essentially different changes in wind properties and (ii) many seemingly controversial trends and variations established in wave properties at different sites in the recent past may reflect the natural spatial variability in the Baltic Sea wave fields.

Decadal changes in the Baltic Sea wave heights

2014 ◽  
Vol 129 ◽  
pp. 86-95 ◽  
Author(s):  
Tarmo Soomere ◽  
Andrus Räämet
Keyword(s):  
Baltic Sea ◽  
The Baltic Sea ◽  
Wave Heights ◽  
The Baltic ◽  
Sea Wave

Equivalent Storm Model for Long-Term Statistics of Sea Storms Off Norway

2018 ◽  
Author(s):  
Valentina Laface ◽  
Anne Karin Magnusson ◽  
Elzbieta M. Bitner-Gregersen ◽  
Magnar Reistad ◽  
Alessandra Romolo ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Wave Model ◽  
Significant Wave ◽  
Storm Intensity ◽  
Statistical Equivalence ◽  
Wave Heights ◽  
Model Time Series ◽  
Two Parameters ◽  
Storm Model

The paper deals with long-term analysis of ocean storms off Norway. Sixty years of wave model time series are considered for the analysis. The input data provide spectral characteristics of both wind and swell seas. The availability of global and partitioned significant wave heights enables the possibility of investigating how swell seas influence the storm shape in terms of growing and decay stages and on how this aspect affects the long-term estimates. The analysis is conducted by means of equivalent storm approach which consists of substituting the sequence of actual storms at a given site with a sequence of equivalent storms whose shape is fixed (such as triangular, power or exponential) and then calculating return periods of storm with given characteristics via analytical solutions derived on the basis of storm shape assumed. This is possible due to statistical equivalence between actual and equivalent storms which in turn leads to the equality of wave risk between actual and equivalent storm sequences at a given site. The equivalent storm associated with an actual one is defined by means of two parameters, related to the storm intensity and duration. The equivalent storm intensity is given by the maximum significant wave height in the actual storm history, while the duration is determined via an iterative procedure. In this paper the exponential shape is considered which is referred as equivalent exponential (EES) storm model. Some aspects related with the storm shape and its influence on return values estimate via EES model are investigated. Further, a sensitivity analysis of EES model to the storm threshold is proposed.

scholarly journals An Extended Poisson test for Detecting the Difference Between the Past and Future Rates of Extremes of Sea wave Heights

2015 ◽  
Vol 116 ◽  
pp. 583-591 ◽  
Author(s):  
Toshikazu Kitano ◽  
Sivaranjani Jayaprasad ◽  
Wataru Kioka
Keyword(s):  
The Past ◽  
Wave Heights ◽  
The Difference ◽  
Sea Wave

Theoretical and Numerical Models to Predict Fracking Debonding Zone and Optimize Perforation Cluster Spacing in Layered Shale

2017 ◽  
Vol 85 (1) ◽  
Author(s):  
Tao Wang ◽  
Zhanli Liu ◽  
Yue Gao ◽  
Qinglei Zeng ◽  
Zhuo Zhuang
Keyword(s):  
Large Scale ◽  
Shear Failure ◽  
Numerical Models ◽  
Fracture Network ◽  
Dimensionless Parameters ◽  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Bedding Planes ◽  
Two Parameters ◽  
Good Agreement

Shale is a typical layered and anisotropic material whose properties are characterized primarily by locally oriented anisotropic clay minerals and naturally formed bedding planes. The debonding of the bedding planes will greatly influence the shale fracking to form a large-scale highly permeable fracture network, named stimulated reservoir volume (SRV). In this paper, both theoretical and numerical models are developed to quantitatively predict the growth of debonding zone in layered shale under fracking, and the good agreement is obtained between the theoretical and numerical prediction results. Two dimensionless parameters are proposed to characterize the conditions of tensile and shear debonding in bedding planes. It is found that debonding is mainly caused by the shear failure of bedding planes in the actual reservoir. Then the theoretical model is applied to design the perforation cluster spacing to optimize SRV, which is important in fracking. If the spacing is too small, there will be overlapping areas of SRV and the fracking efficiency is low. If the spacing is too large, there will be stratum that cannot be stimulated. So another two dimensionless parameters are proposed to evaluate the size and efficiency of stimulating volume at the same time. By maximizing these two parameters, the optimal perforation cluster spacing and SRV can be quantitatively calculated to guide the fracking treatment design. These results are comparable with data from the field engineering.

scholarly journals Sediment transport modeling in deposited bed sewers: unified form of May's equations using the particle swarm optimization algorithm

2017 ◽  
Vol 76 (4) ◽  
pp. 992-1000 ◽  
Author(s):  
Mir Jafar Sadegh Safari ◽  
Akbar Shirzad ◽  
Mirali Mohammadi
Keyword(s):  
Particle Swarm Optimization ◽  
Sediment Transport ◽  
Optimization Algorithm ◽  
Particle Swarm Optimization Algorithm ◽  
Particle Swarm ◽  
Swarm Optimization ◽  
Dimensionless Parameters ◽  
Reliable Model ◽  
Practical Tool ◽  
Two Parameters

May proposed two dimensionless parameters of transport (η) and mobility (Fs) for self-cleansing design of sewers with deposited bed condition. The relationships between those two parameters were introduced in conditional form for specific ranges of Fs, which makes it difficult to use as a practical tool for sewer design. In this study, using the same experimental data used by May and employing the particle swarm optimization algorithm, a unified equation is recommended based on η and Fs. The developed model is compared with original May relationships as well as corresponding models available in the literature. A large amount of data taken from the literature is used for the models' evaluation. The results demonstrate that the developed model in this study is superior to May and other existing models in the literature. Due to the fact that in May's dimensionless parameters more effective variables in the sediment transport process in sewers with deposited bed condition are considered, it is concluded that the revised May equation proposed in this study is a reliable model for sewer design.

scholarly journals Long-term spatial variations in the Baltic Sea wave fields

2010 ◽  
Vol 7 (6) ◽  
pp. 1889-1912
Author(s):  
T. Soomere ◽  
A. Räämet
Keyword(s):  
Baltic Sea ◽  
Spatial Variations ◽  
Extreme Wave ◽  
The Baltic Sea ◽  
Wave Fields ◽  
Wave Heights ◽  
The Baltic ◽  
Wave Properties ◽  
Sea Wave

Abstract. This study focuses on spatial patterns in linear trends of numerically reconstructed basic wave properties (average and extreme wave heights, wave period) in the Baltic Sea. Numerical simulations of wave conditions for 1970–2007, using the WAM wave model and adjusted geostrophic winds, revealed extensive spatial variations in long-term changes in both average and extreme wave heights in the Baltic Sea but almost no changes in the basinwide wave activity and wave periods. There has been a statistically significant decrease in the annual mean significant wave height by more than 10% between the islands of Öland and Gotland and in the southward sea area, and a substantial increase to the south-west of Bornholm, near the coast of Latvia, between Åland and the Swedish mainland, and between the Bothnian Sea and the Bothnian Bay. Variations in extreme wave heights (defined as the threshold for 1% of the highest waves each year) show similar patterns of changes. In several areas the trends in average and extreme wave heights are different. Such a complicated pattern of changes indicates that (i) different regions of the Baltic Sea basin have experienced widespread but essentially different changes in wind properties and (ii) many seemingly controversial trends and variations established in wave properties at different sites in the recent past may reflect the natural spatial variability in the Baltic Sea wave fields.

scholarly journals HEIGHT DISTRIBUTION OF ESTUARINE WAVES

1982 ◽  
Vol 1 (18) ◽  
pp. 9
Author(s):  
V. Barthel
Keyword(s):  
North Sea ◽  
Rayleigh Distribution ◽  
Wave Climate ◽  
Field Investigation ◽  
Height Distribution ◽  
Empirical Distributions ◽  
The North ◽  
Wave Heights ◽  
The North Sea ◽  
Sea Wave

A field investigation program on waves was carried out in the Weser estuary, German Bight of the North Sea. Wave height and period distributions in this complicated wave climate can be approximated by a Rayleigh distribution. Empirical distributions of the wave heights characterise the different regions of the estuary. The presence of wave grouping as well as the group bounded long waves are shown in a few examples. The necessity of further investigations and analysis is highlighted.

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