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The effect of directionality on northern north sea extreme wave design criteria

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The effect of directionality on northern north sea extreme wave design criteria. / Ewans, K.; Jonathan, P.
ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASME, 2007. p. 479-488.

Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSN › Conference contribution/Paper › peer-review

Harvard

Ewans, K & Jonathan, P 2007, The effect of directionality on northern north sea extreme wave design criteria. in ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASME, pp. 479-488. https://doi.org/10.1115/OMAE2007-29657

APA

Ewans, K., & Jonathan, P. (2007). The effect of directionality on northern north sea extreme wave design criteria. In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering (pp. 479-488). ASME. https://doi.org/10.1115/OMAE2007-29657

Vancouver

Ewans K, Jonathan P. The effect of directionality on northern north sea extreme wave design criteria. In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASME. 2007. p. 479-488 doi: 10.1115/OMAE2007-29657

Author

Ewans, K. ; Jonathan, P. / The effect of directionality on northern north sea extreme wave design criteria. ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASME, 2007. pp. 479-488

Bibtex

@inproceedings{8ef49948845842f29cb4b1249a2bcea7,
title = "The effect of directionality on northern north sea extreme wave design criteria",
abstract = "The characteristics of hindcast data for extreme storms at a Northern North Sea location are shown to depend on storm direction, reflecting storm strength and fetch variability.Storm peak Hs over threshold is modelled using a generalised Pareto distribution, the parameters of which are allowed to vary smoothly with direction using a Fourier form. A directionally-varying extreme value threshold is incorporated. The degree of smoothness of extreme value shape and scale with direction is regulated by roughness-penalised maximum likelihood; the optimal value of roughness selected by cross-validation. The characteristics of 100-year storm peak HS, estimated using the directional model differ from those estimated when ignoring the directionality of storms. In particular, the extreme right hand tail of omnidirectional H S100 is longer using the directional model, indicating in this case that ignoring directionality causes underestimation of design criteria. Although storm peak data alone are used for extreme value modelling, the influence of a storm, in directional design sectors other than that containing its storm peak direction, is incorporated by estimating the storm's directional dissipation directly from the data. An automated approach to selection of directional design sectors is described. Directional design criteria are developed using three different approaches, all consistent with an omni-directional storm peak H S non-exceedence probability of 0.5. We suggest a risk-cost criterion, which minimises design cost for a given omni-directional design specification, as an objective basis for optimal selection of directional criteria. Copyright {\textcopyright} 2007 by ASME.",
keywords = "Directionality, Non-exceedence probability, Pareto distribution, Storm strength, Flow patterns, Fourier analysis, Mathematical models, Pareto principle, Probability, Water waves, Storms",
author = "K. Ewans and P. Jonathan",
year = "2007",
doi = "10.1115/OMAE2007-29657",
language = "English",
isbn = "0791842681",
pages = "479--488",
booktitle = "ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering",
publisher = "ASME",

}

RIS

TY - GEN

T1 - The effect of directionality on northern north sea extreme wave design criteria

AU - Ewans, K.

AU - Jonathan, P.

PY - 2007

Y1 - 2007

N2 - The characteristics of hindcast data for extreme storms at a Northern North Sea location are shown to depend on storm direction, reflecting storm strength and fetch variability.Storm peak Hs over threshold is modelled using a generalised Pareto distribution, the parameters of which are allowed to vary smoothly with direction using a Fourier form. A directionally-varying extreme value threshold is incorporated. The degree of smoothness of extreme value shape and scale with direction is regulated by roughness-penalised maximum likelihood; the optimal value of roughness selected by cross-validation. The characteristics of 100-year storm peak HS, estimated using the directional model differ from those estimated when ignoring the directionality of storms. In particular, the extreme right hand tail of omnidirectional H S100 is longer using the directional model, indicating in this case that ignoring directionality causes underestimation of design criteria. Although storm peak data alone are used for extreme value modelling, the influence of a storm, in directional design sectors other than that containing its storm peak direction, is incorporated by estimating the storm's directional dissipation directly from the data. An automated approach to selection of directional design sectors is described. Directional design criteria are developed using three different approaches, all consistent with an omni-directional storm peak H S non-exceedence probability of 0.5. We suggest a risk-cost criterion, which minimises design cost for a given omni-directional design specification, as an objective basis for optimal selection of directional criteria. Copyright © 2007 by ASME.

AB - The characteristics of hindcast data for extreme storms at a Northern North Sea location are shown to depend on storm direction, reflecting storm strength and fetch variability.Storm peak Hs over threshold is modelled using a generalised Pareto distribution, the parameters of which are allowed to vary smoothly with direction using a Fourier form. A directionally-varying extreme value threshold is incorporated. The degree of smoothness of extreme value shape and scale with direction is regulated by roughness-penalised maximum likelihood; the optimal value of roughness selected by cross-validation. The characteristics of 100-year storm peak HS, estimated using the directional model differ from those estimated when ignoring the directionality of storms. In particular, the extreme right hand tail of omnidirectional H S100 is longer using the directional model, indicating in this case that ignoring directionality causes underestimation of design criteria. Although storm peak data alone are used for extreme value modelling, the influence of a storm, in directional design sectors other than that containing its storm peak direction, is incorporated by estimating the storm's directional dissipation directly from the data. An automated approach to selection of directional design sectors is described. Directional design criteria are developed using three different approaches, all consistent with an omni-directional storm peak H S non-exceedence probability of 0.5. We suggest a risk-cost criterion, which minimises design cost for a given omni-directional design specification, as an objective basis for optimal selection of directional criteria. Copyright © 2007 by ASME.

KW - Directionality

KW - Non-exceedence probability

KW - Pareto distribution

KW - Storm strength

KW - Flow patterns

KW - Fourier analysis

KW - Mathematical models

KW - Pareto principle

KW - Probability

KW - Water waves

KW - Storms

U2 - 10.1115/OMAE2007-29657

DO - 10.1115/OMAE2007-29657

M3 - Conference contribution/Paper

SN - 0791842681

SP - 479

EP - 488

BT - ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering

PB - ASME

ER -