Extreme value analysis of tropical cyclone trapped-fetch waves

A trapped-fetch wave (TFW) dataset for all tropical cyclones (TCs) in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea from 1851 to 2005 was created using historical track data, a parametric model depiction of the local TC wind fields, and a Lagrangian TFW model. The wave height at each hourly position along a TFW trajectory was sorted into 2^o X 2^o latitude–longitude grid squares and the marine areas of Atlantic Canada. The data samples in 5 representative grid squares and the 20 marine areas were subjected to statistical analysis to determine if extreme value theory could be used to model the extreme wave heights in the dataset, in particular the peaks-over-threshold approach and the generalized Pareto distribution (GPD). The results of this analysis justified fitting GPD models to the remainder of the climatological TC domain. Using these models a return period calculator was created and added to the suite of risk assessment tools.

A brief review of the analysis procedure and results for the representative grid squares and marine areas will be presented. The risk assessment applications will be discussed and their utility in addressing various questions on extreme TFWs illustrated.