Climate change and North Sea storm surge extremes - an
ensemble study (PRUDENCE)
Katja Woth & Hans von StorchInstitute for Coastal Research
GKSS Research Center
Geesthacht, Germany
Institute for Coastal ResearchGKSS, Germany
• Assessing ongoing change of coastal climate.• Deriving scenarios of plausible, possible futures
of coastal climates.• Special emphasis on wind-related aspects, i.e.,
wind force, storm surges and ocean waves.• Special emphasis on North Sea and Baltic Sea.• Participant in HIPOCAS, PRUDENCE and
ENSEMBLES.
NCEP Globale Reanalysen ( 210 km x 210 km )1958 - 2002
WAM sig. Wellenhöhe und Richtung 21.02.1993 12 UTC
BAW - TELEMAC 2DWasserstand und
barotrope Strömung 21.02.1993 12 UTC
Auflösung zwischen etwa 100 m und 5km
Auflösung etwa 5 x 5 km
Auflösung etwa 50 x 50 km
REMO Windgeschwindigkeit und Richtung 21.02.1993 12 UTC
HIPOCAS:Für Rekonstruktionen verwendete ModellketteGebiet hier: Nordsee und östlicher Nordatlantik
Climate risk assessments done with these models
• Reconstruction of past and ongoing state and change
• PCPnP futures(PCPnP = plausible, consistent, possible but not necessarily probable = scenarios)
Not assimilated into NCEP (Ionic Sea)
Comparison of wind speed statistics with in-situ data: RCM is skillful in describing marine wind statistics
External Forcing – Future Scenarios
EU-Project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change
risks and Effects)
Impact scenarios
today
scenario
GCM
today
scenario
RCMs
scaleglobal local
ImpactImpactmodelmodel
Storm SurgeModel forthe North Sea:
- TRIM 3D
RegionalClimate Models:
- CLM- REMO- HIRHAM- RCAO
Global Climate Model
(HadAM3) IPCC A2
SRES Scenario
(1961-1990 / 2071-2100)
RCAO HIRHAM
CLM REMO5
A2 - CTL: changes in 99 % - iles of wind speed (6 hourly, DJF): west wind sector selected (247.5 to 292.5 deg)
Projections for the future / surge Projections for the future / surge meteorological forcing: HIRHAM / RCAmeteorological forcing: HIRHAM / RCA
Differences in inter-annual percentiles of surge / A2 - CTL: HIRHAM
Differences in inter-annual percentiles of surge / A2 - CTL: RCA
Mean change of winter 95%ile surge levels
Near coastal model cells
SREs emission scenarios: Impact on global sea level
IPC
C, 2
001
According to scenario A2 and the specific set of GCM / RCMs, water level may rise in extreme situations by as much as
40 cm + 30 cm = 70 cm
along the German North Sea coast.
Conclusions• Dynamical models have been demonstrated to be a
useful tool to describe the statistics, and changes thereof, of wind-related phenomena in coastal seas – wind force, storm surge, coastal currents and ocean waves.
• An ensemble of regionalizations, derived from one global A2 scenario, results in rather similar changes of regional wind over the North sea and the associated change of surge levels.
• Along the German North Sea coast, water levels may rise by up to 70 cm - of which 40 cm are due to mean sea level rise and 30 cm to different storm patterns.