Tide-surge-wave modelling and forecasting in the Mediterranean Sea with focus on the Italian coast

A tide-surge-wave modelling system, called Kassandra, was developed for the Mediterranean Sea. It consists of a 3-D finite element hydrodynamic model (SHYFEM), including a tidal model and a third generation finite element spectral wave model (WWMII) coupled to the hydrodynamic model. The numerical grid of the hydrodynamic and wave models covers the whole Mediterranean with variable resolution. The comparison with coastal tide gauge stations along the Italian peninsula results in a root sum square error for the main tidal components equal to 1.44 cm. The operational implementation of the Kassandra storm surge system through the use of a high resolution meteorological model chain (GFS, BOLAM, MOLOCH) allows accurate forecast of total water level and wave characteristics. The root mean square error for the first day of forecast is 5 cm for the total water level and 22 cm for the significant wave height. Simulation results indicate that the use of a 3-D approach with a depth-varying loading factor and the inclusion of the non-linear interaction between tides and surge improve significantly the model performance in the Italian coast.

► We developed a tide-surge-wave finite element model for the Mediterranean Sea. ► The model compare well with observations taken along the Italian peninsula. ► 3-D approach, tide-surge interaction and depth varying loading factor reduce model error. ► The use of high resolution meteorological model allows high accuracy marine forecasts.