iahr 2015 - operational wave forecasts in the southern north sea, gautier, deltares, 30062015
TRANSCRIPT
Caroline Gautier and Sofia CairesJune 30th, 2015
Operational Wave Forecasts in theSouthern North SeaIAHR special session: Coasts at Threat in Europe
June 30th, 2015
Coasts at Threat in Europe
SWAN-North Sea for operational wave forecasts- Waves during extreme storm surges- Waves effecting vessel operations in approach channel
2
SWAN-North Sea for operational wave forecasts
June 30th, 2015 3
Model set up SWAN-North Sea
June 30th, 2015 4
SWAN-DCSMRectangularArea:1500 km x 1700 kmCell size:3.6 km x 3.6 km
SWAN-ZUNOCurvilinearArea:770 km x 750 kmCell size:200 m - 2 km x200 m - 2 km
Model set up SWAN-North Sea
Wave boundary conditions for SWAN-DCSM:WAM model by ECMWF (30 freq x 24 dir) 0:00 6:00 12:00 18:00…
dt = 6 hrWind:KNMI’s HIRLAM11-v7.2 model 0:00 6:00 12:00 18:00…
dt = 1hrWater levels:WAQUA DCSMv6 0:00 6:00 12:00 18:00…
dt = 1hrCurrents (SWAN-ZUNO only):WAQUA DCSMv6 0:00 6:00 12:00 18:00…
dt = 1hrBathymetry:based on WAQUA DCSMv6 and ZUNOv4 (before calibration)
June 30th, 2015 5
Model set up SWAN-North Sea
June 30th, 2015 6
every 6 hour, a new SWAN run is started
6 hours hindcast + 48 hours forecasttime step: 1 hr
Model calibration SWAN-North Sea
June 30th, 2015 7
1. WEO2. AZB123. ELD4. K135. IJMUN6. EPL
freq [Hz]
E[m
2/H
z]
0.0 0.1 0.2 0.3 0.4 0.5
HE10, Hm0, Tm-1,0
Model calibration SWAN-North Sea
June 30th, 2015 8
Observation
Komen; =0Cfric=0.038(SWAN North Sea)
Westhuysen
Komen; =1(presently default inSWAN)
Hm
0[m
]H
E10
[m]
T m-1
,0[s
]U
10[m
/s]
Westhuysen,Cfric=0.048
Komen; =0Cfric=0.028
Komen; =0.5Cfric=0.028
Model calibration SWAN-North Sea
June 30th, 2015 9
• Reducing bottom friction (from 0.038 to 0.028) improves the bias of HE10
• Westhuysen whitecaping gives smallest bias• Komen whitecapping ( =0) gives least scatter in HE10
0.5 < HE10 < 1.5 [%] Hm0 [%] Tm-1,0 [%] 0.5 < HE10 < 1.5 [%] Hm0 [%] Tm-1,0 [%]
Model calibration SWAN-North Sea
June 30th, 2015 10
0.5 < HE10 < 1.5 [%] Hm0 [%] Tm-1,0 [%]
Conclusions SWAN-North Sea
June 30th, 2015 11
• SWAN-North Sea consists of:SWAN-DCSM and the nested SWAN-ZUNO
• Input comes from: - HIRLAM wind fields- ECMWF-WAM off shore waves- WAQUA water levels and currents
• HE10 is a sensitive parameter, especially for whitecapping formulation
• Improved settings: HE10 bias= -8% scatter= 33%Hm0 bias= 4% scatter= 16%Tm-1,0 bias= -11% scatter= 9%
HE10 Hm0 Tm-1,0
observations observations observations
SWAN
-ZU
NO
SWAN
-ZU
NO
SWAN
-ZU
NO
IAHR 2015 - Predicting long waves and their coastal impacts, Roelvink, Unesco IHE Deltares, 20150702
IAHR 2015 - The new Delta Flume for large-scale physical model testing, Van Gent, Deltares, 29062015