Extreme wave statistics within the Mouth of the Columbia River

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Authors
Johnston, Carter L.
Subjects
RIVET II
Extreme Waves
Rogue Waves
Histogram
Nonlinear
WRD
Wave Buoys
Awesome
Amazing
Mouth of Columbia River
MCR
Bar.
Advisors
Herbers, Thomas H. C.
MacMahan, Jamie H.
Date of Issue
2014-12
Date
Dec-14
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
Rogue waves have presented unpredictable, dire hazards to mariners since the dawn of seafaring. Even in benign seas, isolated rogue waves can severely endanger ships and crews, even accounting for their disappearance. Better understanding of rogue wave generation will enhance safety of maritime operations. This study examines surface height data from wave resolving drifters (WRDs) deployed in groups of 30–50 in the Mouth of the Columbia River (MCR) during the peak of ebb tide in May and June of 2013. Over three separate collection days, effects of opposing currents and bathymetry on swell and wind waves were analyzed as WRDs headed to sea from the MCR. Wave significance was identified based on the local sea state within 1 km of the drifter location. Wave height histograms were calculated from regional wave ensembles and compared with the theoretical Rayleigh distribution of a narrow band, Gaussian wave field. Generally, wave height data in the MCR follow Rayleigh distribution well. Areas over shallower bathymetry of the MCR Bar and predominant waves from the west create intense sea state amplification and rogue wave occurrence, and right-tail deviation from the Rayleigh pdf. Isolated extreme waves and trains of large waves were observed on the Bar.
Type
Thesis
Description
Series/Report No
Department
Oceanography
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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