1. Hans Burchard Leibniz Institute for Baltic Sea Research Warnemünde, Germany Cooperation: Thomas Badewien 1, Johannes Becherer 2, Götz Flöser 3, Ulf Gräwe 2, Volker Mohrholz 2, Rolf Riethmüller 3, Joanna Staneva 3, Lars Umlauf 2 1. 1. University Oldenburg, Germany 2. 2. Leibniz Institute for Baltic Sea Research Warnemünde, Germany 3. 3. Helmholtz Center Geesthacht, Institute for Coastal Research, Germany Modelling the turbulent Wadden Sea: What’s needed most

2. Warming Precipitation Weak tidal mixing: vertically stratified Strong tidal mixing: horizontally stratified LandOcean Downward surface buoyancy flux Thermohaline estuarine circulation Sea bed River? The Wadden Sea circulation in a nutshell Compare to:

3. Climatology: Salinity difference HW-NW Burchard et al. (JPO 2008)

4. Climatology: Temperature difference HW-LW Burchard et al. (JPO 2008)

5. Climatology: Density difference HW-LW Burchard et al. (JPO 2008)

6. MacCready & Geyer (2010) after Jay & Musiak (1994) Longitudinal density gradients & tidal oscillations lead to: e.g., tidal straining 75% level

7. Does this happen in nature?

8. Becherer et al. (in prep.) 75% levelfloodebb

9. Thermohaline estuarine circulation (observed) Becherer et al. (in prep.)

10. Modelling the impact of density gradients on SPM transport With density differences V / km 3 Burchard et al. (JPO 2008) Without density differences Relative SPM content V / km 3 Sylt (D) Romo (DK)

11. Seasonality of tidal forcing Müller et al. (in prep.) Gräwe et al. (in prep.) How does this affect sediment transport due to tidal asymmetries (M 4 )?

12. Sea level rise & tidal flat growth (Danish Wadden Sea) Data and graphics from Morten Pejrup, Copenhagen University ?

13. Model system based on GETM: NA: 5.4 km X 5.4 km (2D) NSBS: 1.8 km X 1.8 km (3D) SNS: 600 m X 600 m (3D) Wadden Sea: 200 m X 200 m (3D) PACE project (NWO-BMBF): „The future of the Wadden Sea sediment fluxes: Still keeping pace with sea level rise?“ (2011-2014) Wadden Sea model Gräwe et al., in prep.

14. Tides in the Wadden Sea (as seen in 200 m resolution model) Gräwe et al., in prep.

15. Wadden Sea model: M 4 tidal elevations (phase and amplitude) as validation data. Gräwe et al., in prep.

16. Sea surface salinity in the Wadden Sea (as seen in 200 m resolution model) Personal communication Matias Duran Matute (NIOZ)

17. atmospheric chemistry atmospheric physics benthic geoecology benthic biogeochemistry cohesive sediments adaptive ecosystem & element cycles waves river discharge MOdular System for Shelf and Coasts (MOSSCo) ocean physics ocean BGC water physics

18. Major messages The Wadden Sea is as complex as other marine systems. An Earth system modelling approach is needed to understand its sensitivity to climate change and direct human intervention. Components of (multi-scale) Wadden Sea Earth system model: 3D baroclinic hydrodynamics Sediment (sand & mud) transport model Morphodynamic module Benthic & pelagic biogeochemical modules Atmospheric module Wave module Hydrological module etc...... all interactively linked