Bivariate regional extreme value analysis for significant wave height and wave period

Abstract

This paper presents a bivariate regional frequency analysis applied to vectors of extreme significant wave heights and concurrent zero up-crossing wave period over an area in the North Atlantic ocean. The analysis is based on a bivariate index-wave/period approach and the assumption of a common regional growth curve within homogeneous regions. The main benefits of performing a regional frequency analysis as opposed to at-site analysis based on data from one location only are twofold: It may give more accurate predictions of extreme conditions due to the increased amount of data made available for the statistical analysis, and results for ungauged locations can be obtained easily by interpolation of the index wave/period. Previous regional frequency analyses for ocean waves have been restricted to the univariate case. However, design conditions for marine and coastal structures will typically be characterised by the joint distribution of several metocean variables. Hence, it is useful to perform multivariate analyses of the extreme ocean environment. As a minimum, information about the joint distribution of significant wave height and period is often needed. This paper outlines the various steps involved in a bivariate regional frequency analysis and presents the results of such an analysis applied to data covering the North Atlantic ocean over a period of 30 years.