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Storm surge modelling in the Mediterranean Sea with focus on the Italian coast. Christian Ferrarin 1.2 . Georg Umgiesser 1 . Andrea Cucco 2 . Marco Bajo 1 1. ISMAR-CNR. Venice. Italy. 2. IAMC-CNR. Oristano. Italy. Christian Ferrarin : c.ferrarin@ismar.cnr.it. Objective.
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Storm surge modelling in the Mediterranean Sea with focus on the Italian coast Christian Ferrarin1.2. Georg Umgiesser1. Andrea Cucco2. Marco Bajo1 1. ISMAR-CNR. Venice. Italy. 2. IAMC-CNR. Oristano. Italy. Christian Ferrarin : c.ferrarin@ismar.cnr.it
Objective The goal of this research is to describe/predict the storm surge in the Mediterranean Sea with focus on the Italian coast, through the application of high resolution numerical models. • The TOTAL WATER LEVEL is given by: • Tidal Oscillation • Meteorological Surge • Wave set-up / set-down
Finite element tide-surge-wave modelling system Hydrodynamic Model Meteorological Model MODEL FRAMEWORK STORM SURGE Spectral Wave Model
SHYFEM ModelShallow water HYdrodynamic Finite ElementModel SHYFEM ModelShallow water HYdrodynamic Finite Element Model Bottom stress Pressure gradient Wind stress Loading tide Wave Radiation stress Potential tide • = water level H = water depth • g = gravity • f = Coriolis parameter • U.,V = velocities • Ah = hor. diff. coeff. • pa = atm. pressure • η = equilibrium tide • α = Love number • β = loading factor
Finite element wave model WWM Finite element wave model based on the spectral action balance equation (Hsu et al. 2005): N = wave action density S = source term • Operator Splitting Methods (OSM) • 1st and 2nd Step – Spectral part • 2nd Step – Geographical space • 3rd Step – Integration of the source terms
Model domain • 646218 nodes • 117714 elements • Resolution: • open sea 15-20 km • coast 5 km • Italian coast 1.5 km
Model set up • Hydrodynamic: • 2D borotropic • Smith & Banke formulation • Time step: 300 s (adaptive) • Wave: • 18 directions • 18 frequency [0.05 ... 0.5] • Time step = 600 s • FORCING: • ECMWF wind & pressure • FES2004 tide at Gibraltar Strait • Body + earth + load tides • 4 diurnal (K1, O1, P1, Q1) • 4 semidiurnal (M2, S2, N2, K2) • 3 long term (Mf, Mm, Ssa)
Model results 2: Residual differences Line = median Box = 25th to 75th percentile Wisker = 1.5 * IQR Star = average value