Comparing different extreme wave analysis models for wave climate assessment along the Italian coast

Abstract

By utilizing various statistical models to quantify the return levels of extreme significant wave height this study seeks to achieve two objectives: the updating of the state-of-the-art concerning extreme wave analysis along the Italian coast and the creation of a long-term predictive model. To these ends, four different methods widely used in the field of metocean engineering are employed to analyze both buoy data (Rete Ondametrica Nazionale, RON) and wave data obtained by means of dynamical hindcasting techniques such as the forecast/hindcast operational model chain in use at the University of Genoa (www.dicca.unige.it/meteocean). Return levels are estimated by the Goda method, the Generalized Extreme Value (GEV) and the Generalized Pareto Distribution–Poisson point process models and the Equivalent Triangular Storm (ETS) algorithm. All models follow the Peak-Over-Threshold (POT) approach which require an optimal threshold implementation, save for the GEV analysis, which is applied to model significant wave height maxima pertaining to time-blocks. The models exhibit different performance characteristics, presented here and treated in depth. In general, noteworthy versatility characterizes the GPD–Poisson model, which often recovers Goda results, while the GEV and ETS models exhibit limitations in assessment of a variety of wave fields, greatly diversified in a semi-closed basin such as the Mediterranean Sea. Long-term estimates have been provided by means of the most appropriate model selected, thus offering a complete overview of wave climate in the Mediterranean basin based on wave hindcast data.