STATISTICS FOR EXTREME SEA CURRENTS

Estimates of various characteristics of extreme sea currents, such as speeds and their directions, are required when designing offshore stru ctures. This paper extends standard statistical methods for extreme va lues to handle the directionality, temporal dependence and tidal non-s tationarity that are present in sea current extremes. The methods are applied to a short period of data from the Inner Dowsing Light Tower i n the North Sea, Substantial benefits, over existing methods, are obta ined from our analysis of the sea current by decomposing it into tide and surge currents, In particular, we find that at the Inner Dowsing t he strong directionality in extreme sea current speeds is completely e xplained by the tidal current and directionality in the non-extreme su rge currents. This finding aids model fitting and extrapolation.