Storm surge modelling in the Storm surge modelling in the Mediterranean Sea with focus on Mediterranean Sea with focus on
the Italian coastthe Italian coast
Christian Ferrarin1.2. Georg Umgiesser1. Andrea Cucco2. Marco Bajo1
1. ISMAR-CNR. Venice. Italy. 2. IAMC-CNR. Oristano. Italy.
Christian Ferrarin : [email protected]
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.
ObjectiveObjective
The TOTAL WATER LEVEL is given by:• Tidal Oscillation• Meteorological Surge• Wave set-up / set-down
Finite element tide-surge-wave modelling system
Meteorological Model
HydrodynamicModel
SpectralWave Model
STORM SURGE
MO
DEL F
RA
MEW
OR
K
i
iy z
vkτ
SHYFEM ModelShallow water HYdrodynamic Finite Element Model
SHYFEM ModelShallow water HYdrodynamic Finite Element Model
xgH
xgH
H
F
y
U
x
UA
x
p
x
ζgHfV
y
Uv
x
Uu
t
U xh
sx
bx
a
2
2
2
2111
ygH
ygH
H
F
y
V
x
VA
y
p
y
ζgHfU
y
Vv
x
Vu
t
V yh
sy
by
a
2
2
2
2111
0
y
V
x
U
t
= water levelH = water depthg = gravityf = Coriolis parameterU.,V = velocitiesAh = hor. diff. coeff.pa = atm. pressureη = equilibrium tideα = Love numberβ = loading factor
Potentialtide
Loadingtide
WaveRadiation
stress
Windstress
Pressuregradient
Bottomstress
Charnockg
uz
BankeSmithuC
uC
s
wd
wdas
2*
0
3
2
&10)066.063.0(
1/62
22
=
=
HkCC
gc
H
vuuc
sb
bb
Operator Splitting Methods (OSM) 1st and 2nd Step – Spectral part
2nd Step – Geographical space
3rd Step – Integration of the source terms
*
*000; on 0,t
Nc N N N t
t
***
** ** *** **00 ; on 0,x y t t t
Nc N c N N N t
t x y
****
**** ***,** 0; on 0,totN t t t
NS N N t
t
**
* ** *00; on 0,t t t
Nc N N N t
t
Finite element wave model WWM
totalyx S
NCNC
y
NC
x
NC
t
N
)()()()(
Finite element wave model based on the spectral action balance equation (Hsu et al. 2005):
N = wave action density S = source term
Model domainModel domain
646218 nodes117714 elements
Resolution:• open sea 15-20 km• coast 5 km• Italian coast 1.5 km
Model set upModel set up
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)
Hydrodynamic:• 2D borotropic• Smith & Banke formulation• Time step: 300 s (adaptive)
Wave:• 18 directions• 18 frequency [0.05 ... 0.5]• Time step = 600 s
Model results 1: tideModel results 1: tide
Amp Pha Amp Pha Amp Pha Amp Pha Amp Pha Amp Pha Amp Pha Amp Pha-0,21 -1,06 -0,10 -4,33 -0,15 1,27 -0,20 3,28 0,34 2,03 0,44 -0,40 0,25 19,79 -0,06 -6,510,83 6,81 0,35 8,25 0,25 8,29 0,34 9,93 0,42 69,92 0,59 18,27 0,30 23,39 0,16 14,23
K1 O1 P1 Q1
AverageRMSE
M2 S2 N2 K2
1,07 0,65 1,19 0,811,62 1,09 1,54 0,39Tsimplis
D(cm) M2 S2 K1 O1
SHYFEM
0
5
10
15
20
25
0 5 10 15 20 25
Mo
delle
d A
mp
litu
de
(cm
)
Observed Amplitude (cm)
M2
K1
0
30
60
90
120
150
180
210
240
270
300
330
360
0 30 60 90 120 150 180 210 240 270 300 330 360
Mo
delle
d P
ha
se (d
eg
)
Observed Phase (deg)
M2
K1
Model results 2: Model results 2: Residual Residual differencesdifferences
StationRMSE [cm] CORR BIAS [cm] SI
ID Name1 Trieste 0.11 0.70 -0.02 1.072 Venezia 0.12 0.76 -0.07 0.983 Ravenna 0.09 0.75 0.00 0.864 Ancona 0.12 0.78 0.09 1.355 Ortona 0.15 0.72 0.12 1.616 Vieste 0.19 0.64 0.17 1.917 Bari 0.22 0.67 0.20 2.028 Otranto 0.30 0.57 0.29 2.349 Taranto 0.26 0.56 0.25 2.27
10Crotone 0.24 0.49 0.22 2.2211Reggio Cal. 0.25 0.55 0.24 2.3012Palinuro 0.17 0.56 0.16 2.0613Salerno 0.19 0.53 0.18 2.1514Napoli 0.16 0.55 0.15 2.0115Civitav 0.10 0.57 0.07 1.5816Livorno 0.09 0.65 0.06 1.3917Genova 0.07 0.68 -0.04 1.0218 Imperia 0.06 0.67 -0.01 0.9219Messina 0.11 0.59 0.09 1.7420Palermo 0.08 0.59 -0.06 1.1921Porto Emp. 0.10 0.48 0.08 1.7922Catania 0.06 0.66 0.01 1.0523Lampedusa 0.08 0.50 -0.04 1.2424Cagliari 0.16 0.53 -0.14 1.8025Carloforte 0.13 0.57 -0.11 1.6226Porto Torres 0.12 0.60 -0.11 1.46
AVERAGE 0.14 0.61 0.07 1.61
Model results 2: Model results 2: Residual Residual differencesdifferences
Line = medianBox = 25th to 75th percentileWisker = 1.5 * IQRStar = average value