Presentation on theme: "Katja Woth & Hans von Storch"— Presentation transcript:
1 Katja Woth & Hans von Storch Climate change and North Sea storm surge extremes - an ensemble study (PRUDENCE)Katja Woth & Hans von StorchInstitute for Coastal ResearchGKSS Research CenterGeesthacht, GermanyAbstract Reference Number: 251Abstract Title: Climate change and North Sea storm surge extremes - an ensemble study (PRUDENCE)Paper Number: A51F-01Presentation Type: OralPresentation Date: Friday, 17 DecemberLocation: 3016Starting Time: 08:04Time allotted: Time Allotted: 12 minutesClimate change and North Sea storm surge extremes - an ensemble study (PRUDENCE)Hans von Storch & Katja WothPossible changes in North Sea storm surge climate are studied in a systematic manner.Following up on previous studies, we use a tide-surge model to derive storm surge climateand extremes from atmospheric conditions under present-day and enhanced greenhouse gasconditions. Results for modeled storm surges obtained by using regional model output fromfour RCMs, namely CLM (GKSS), RCAO (SMHI), REMO5 (MPI) and HIRHAM (DMI) arepresented.The atmospheric regional simulations were prepared within the EU project PRUDENCE. Theresearch strategy of PRUDENCE is to compare simulations of different regional models(RCMs) driven by the same global control and climate change simulations. These globalconditions, representative for and were prepared by the Hadley Centerbased on the IPCC A2 SRES scenario. The effect on windiness of the enhanced greenhousegas conditions, projected by these four regional climate models was in all cases similar,namely a moderate increase of high wind speeds in most parts of the North Sea during winter.These simulated surface wind and pressure data have been used to run a storm surge model.We show the expected storm-related changes in different storm surge parameters. Forinstance, the largest increase of high water levels, defined as the 99.5%ile during wintersampled every half hour would have to be expected along the southern and eastern North Seacoast, with maximum values of around 30 cm, which is beyond the range of normal year-toyearvariations. Similar results can be found for all four experiments. Together with theexpected rise of mean water levels of 40 cm by IPCC (2001), the total increase is 70 cm at theend of the 21st century under the assumptions of the rather severe A2 scenario. If an ECHAMscenarioA2 is used, quantitatively similar results are obtained, but in that case there are alsosignificant increases along parts of the UK coast.
2 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.
3 NCEP Globale Reanalysen ( 210 km x 210 km ) 1958 - 2002 BAW - TELEMAC 2D Wasserstand und barotrope Strömung UTCREMO Windgeschwindigkeit und Richtung UTCHIPOCAS: Für Rekonstruktionen verwendete ModellketteGebiet hier: Nordsee und östlicher NordatlantikWAM sig. Wellenhöhe und Richtung UTCRekonstruktionen am Beispiel einer neueren Arbeit, dem HIPOCAS HindcastAuflösung etwa 50 x 50 kmAuflösung zwischen etwa 100 m und 5kmAuflösung etwa 5 x 5 km
4 Climate risk assessments done with these models Reconstruction of past and ongoing state and changePCPnP futures (PCPnP = plausible, consistent, possible but not necessarily probable = scenarios)
5 Comparison of wind speed statistics with in-situ data: RCM is skillful in describing marine wind statisticsNot assimilated into NCEP (Ionic Sea)These plots are the quantile-quantile diagrams (REMO & NCEP Vs Observations) for 10-m wind speed at 2 buoys station. The first one is an Atlantic offshore buoy (ZBGSO, located at48.7N,12.40W), already assimilated by NCEP. The second one shows results from a Mediterranean buoy (ZATOS, located at 39.96N, 24.72E, Aegean Sea), whose data have NOT been previously assimilated by NCEP.
6 External Forcing – Future Scenarios THE IPCC…scenarios corresponding to different storylines assume diff. Emission scenarios.The main scenario characteristics are described in the Box. A2 assumes..…B2 assumes… with ….and … producing therefore lower emissions and less future warming than A2External Forcing – Future Scenarios
7 EU-Project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects)GCMRCMsRegional Climate Models:CLM - REMO - HIRHAM - RCAOGlobal Climate Model (HadAM3) IPCC A2 SRES Scenario ( / )todaytodayStorm Surge Model for the North Sea:- TRIM 3DImpactmodelImpact scenariosscenarioscenariogloballocalscale
8 A2 - CTL: changes in 99 % - iles of wind speed (6 hourly, DJF): west wind sector selected (247.5 to deg)HIRHAMRCAOREMO5CLM
9 Projections for the future / surge meteorological forcing: HIRHAM / RCA Differences in inter-annual percentiles of surge / A2 - CTL: HIRHAMDifferences in inter-annual percentiles of surge / A2 - CTL: RCA
10 Mean change of winter 95%ile surge levels Near coastal model cells
11 SREs emission scenarios: Impact on global sea level According to scenario A2 and the specific set of GCM / RCMs, water level may rise in extreme situations by as much as40 cm + 30 cm = 70 cmalong the German North Sea coast.IPCC, 2001SREs emission scenarios: Impact on global sea level
12 ConclusionsDynamical 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.