Joanna Staneva, Kathrin Wahle and Emil Stanev January 2014, Rincon Beach Resort, Puerto Rico

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1 3rd GODAE OceanView Coastal Oceans and Shelf Seas Task Team (COSS-TT) International Coordination Workshop Joanna Staneva, Kathrin Wahle and Emil Stanev January 2014, Rincon Beach Resort, Puerto Rico

2 Outline Motivation Numerical Modelling Model Validations Extreme events Sediment dynamics Summary Aims of this talk Address regional observations and predictions with a focus on the German Bight and Wadden Sea

Motivation Coastal Observing System for Northern and Arctic Seas coordinated by HZG pre-operational system joining observations and numerical models (WAM, GETM, SPM) observations: in-situ

3 Motivation Coastal Observing System for Northern and Arctic Seas coordinated by HZG pre-operational system joining observations and numerical models (WAM, GETM, SPM) observations: in-situ measurements from fixed (piles and buoys) and mobile (FerryBox) platforms remotely sensed data from shore by HF-radar and from space by satellite forecasting suite include nested wave model (WAM) 3-D hydrodynamic model (GETM) running in data-assimilation mode SPM model motivation is the continuous provision of near real-time products from pre-operational service main characteristic of the system is the integrated approach combining observations and numerical modeling reduce prediction errors at coastal scales

4 Numerical Models WAM SPM GOTM GETM

30 s 2 open boundaries (S and N) German Bight Dl=Df= 1 km, Time step = 10 s 2 open boundaries (W and

5 Nested modelling system Atmospheric forcing (1 hr DWD atm. data), 1-hr river run-off, Open BC tides, u,v, T and S North Sea-Baltic Sea Dl=Df= 3 min, Time step = 30 s 2 open boundaries (S and N) German Bight Dl=Df= 1 km, Time step = 10 s 2 open boundaries (W and N) Wadden Sea Dl=Df= 200 m, Time step = 3 s 3 open boundaries (W, N and E) Sylt-Römö Dl=Df= 200 m, Time step = 3 s 3 open boundaries (W, N and S)

6 Nested models Sea level

7 SST MARNET vs. GETM German Bight NSboje II FI NO NSboje III Germa n Bight Elb e

8 Operational Wave Model System for the North Sea and German Bight GWAM data assimilation Jason2 Randwerte DWD (operationell) EWAM HZG : prä-operationelle Seegangsvorhersage im Rahmen von COSYNA seit September Räumliche Auflösung : Nordsee ~ 5 km, Deutsche Bucht ~ 900 m (zweimal pro Tag eine 24-stündige 8

9 WAM Validation

10 COSYNA

12 Model Developments GETM&GOTM Developments The original versions of GETM and GOTM were modified to account for the following: 3D radiation stress due to the transfer of momentum by waves (Mellor 2008) gradient of the radiation stress becomes important for the mean water level setup and for longshore currents generated by waves in the surf zone. turbulent kinetic energy due to waves friction (wave breaking/white capping and bottom dissipation) affect the tidal current profiles in shallow areas, may deepen the surface mixed layer WAM Developments (Cycle 4.5.3) source function integration scheme of Hersbach and Janssen (1999) reformulated dissipation source function of Bidlot, et al (2005, 2007) and Janssen (2008) depth induced wave breaking of Battjes & Janssen (1978)

13 Impact of Hydrodynamic Forcing on Waves in the open North Sea nearly no difference is found significant differences (30% hs, 10-15% tm1) near the coast and in the Wadden Sea (mainly due to water depth changes) small areas where STD of tm1 up to 30% (Doppler Shift)

14 Buoy `Elbe - Time Series

15 Buoy `Elbe - Wave Spectra

16 Buoy `Hoernum Tief - Wave Spectra

17 Impact of Wave Forcing on hydrodynamics: Validation with Tide Gauges

18 Impact of Wave Forcing on hydrodynamics Validation with ADCP

19 Hurricane Xavier on

20 Significant wave height during Xavier, December, 2013

21 Influence of coupling with waves on the sea level Corr1=0.951 Corr2=0.893 Corr1=0.943 Corr2=0.864 Corr1=0.923 Corr2=0.887 Corr1=0.964 Corr2=0.896

22 Effects on coupling with waves

23 Taken from Die Hurricane Britta on 1. November, 2006 is assumed as one of the worst for the last 100 years in the lower Saxony German coast ikeroog Juist Wilhemshaven Carolinesiel

24 ... Britta at In Carolinensiel one caravan is swimming... or a ship parked instead of cars This sign must be respected!

25 ECMWF Atmospheric Analyses Data (Hurrikane Brita: )

26 Sea level WATT

27 Surface temperature

28 Evolution of the vertical stratification Watt Station Wadden Sea model WATT

29 Atmospheric conditions during Britta Sensitivity EXPERIMENTS Air temperature Wind EXP1 real real EXP2 filtered filtered EXP3 real filtered EXP4 filtered real

30 Sensitivity experiments evolution of the vertical profile of the temperature anomaly

... Coupled with Sediment Transport Model 3D

forced by waves and tides Areas of Application:

31 ... Coupled with Sediment Transport Model 3D equations Two classes of sediment (mud and sand) Complex physical parameterizations Calibrated to present day observations Hydrodynamic model forced by waves and tides Areas of Application: East Frisian Wadden Sea German Bight (on-going work) North Sea

32 Validation of Sediment Transport Model Against Fine Resolution Satelite Data Surface SPM: Numerical Simulations and MERIS data

33 SPM Variability (top- with waves, bottom- no waves)

34 SPM Variability (top- with waves, bottom- no waves)

35 Summary Nested-grid coupled models are set-up and applied to study the wave-, hydro- and sediment dynamics of the German Bight and the Wadden Sea Synergy between data and modelling shows promissing results we have analysed the impact of hydrodynamics on WAM in the open North Sea nearly no impact significant impact) in the shallow water areas near the coast and in the Wadden Sea impact of waves on the GETM results: in the open North Sea the impact is weak significant impact in the shallow water areas near the coast, in the Wadden Sea and in tidal inlets impact of wave forcing on the SPM dynamics : significant impact of SPM dynamics on waves in both open and shallow water areas better agreement with observations once wave dynamics is included in the SPM coupled system

Wave penetration in a tidal inlet system during a severe winter storm

Alkyon Hydraulic Consultancy & Research Wave penetration in a tidal inlet system during a severe winter storm Gerbrant van Vledder 1 Jeroen Adema 1, Olger Koop 1, François Enet 1 André van der Westhuysen