Transcript Climate change and North Sea storm surge extremes

Climate change and North Sea
storm surge extremes - an
ensemble study (PRUDENCE)
Katja Woth & Hans von Storch
Institute for Coastal Research
GKSS Research Center
Geesthacht, Germany
Institute for
Coastal Research
GKSS, 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
HIPOCAS:
REMO Windgeschwindigkeit und
Richtung 21.02.1993 12 UTC
Für Rekonstruktionen
verwendete Modellkette
Gebiet hier: Nordsee und
östlicher Nordatlantik
BAW - TELEMAC 2D
Wasserstand und
barotrope Strömung
21.02.1993 12 UTC
WAM sig. Wellenhöhe und
Richtung 21.02.1993 12 UTC
Auflösung etwa 50 x 50
km
Auflösung etwa 5 x 5 km
Auflösung zwischen
etwa 100 m und 5km
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)
Comparison of wind speed statistics with in-situ data:
RCM is skillful in describing marine wind statistics
Not assimilated into NCEP
(Ionic Sea)
External Forcing – Future Scenarios
EU-Project PRUDENCE
(Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change
risks and Effects)
GCM
Global
Climate
today
Model
(HadAM3)
IPCC A2
SRES
Scenario
scenario
(1961-1990
/
2071-2100)
global
RCMs
Regional
Climate
Models:
today
- CLM
- REMO
- HIRHAM
-scenario
RCAO
Storm Surge
Model for
theImpact
North Sea:
model
Impact
scenarios
- TRIM 3D
scale
local
A2 - CTL: changes in 99 % - iles of wind speed (6 hourly, DJF): west wind
sector selected (247.5 to 292.5 deg)
HIRHAM
RCAO
REMO5
CLM
Projections for the future / surge
meteorological 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
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
SREs emission scenarios: Impact on global sea level
IPCC, 2001
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.