Hans BurchardLeibniz Institute for Baltic Sea Research Warnemünde, Germany

Cooperation: Thomas Badewien1, Johannes Becherer2, Götz Flöser3, Ulf Gräwe2, Volker Mohrholz2,

Rolf Riethmüller3, Joanna Staneva3, Lars Umlauf2

1. 1. University Oldenburg, Germany2. 2. Leibniz Institute for Baltic Sea Research Warnemünde, Germany3. 3. Helmholtz Center Geesthacht, Institute for Coastal Research, Germany

Modelling the turbulent Wadden Sea:

What’s needed most

Warming Precipitation

Weak tidal mixing: vertically stratified

Strong tidal mixing: horizontally stratified

Land Ocean

Downward surface buoyancy flux

Thermohaline estuarine circulation

Sea bed

River?

The Wadden Sea circulation in a nutshell

Compare to:

Climatology: Salinity difference HW-NW

Burchard et al. (JPO 2008)

Climatology: Temperature difference HW-LW

Burchard et al. (JPO 2008)

Climatology: Density difference HW-LW

Burchard et al. (JPO 2008)

MacCready & Geyer (2010) after Jay & Musiak (1994)

Longitudinal density gradients & tidal oscillations lead to:

e.g., tidal straining

75% level

75% level

Does this happen in nature?

Becherer et al. (in prep.)

75% level flood ebb

Thermohaline estuarine circulation (observed)

Becherer et al. (in prep.)

Modelling the impactof density gradientson SPM transport

With density differences

V /

km3

Burchard et al. (JPO 2008)

Without density differences

Relative SPM content

Relative SPM content

V

/ km

3

Sylt (D)

Romo (DK)

Seasonality of tidal forcing

Müller et al. (in prep.)

Gräwe et al. (in prep.)

How does this affect sediment transport due to tidal asymmetries (M4)?

Sea level rise & tidal flat growth (Danish Wadden Sea)

Data and graphics from Morten Pejrup, Copenhagen University

?

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.

Tides in the Wadden Sea (as seen in 200 m resolution model)

Gräwe et al., in prep.

Wadden Sea model:

M4 tidal elevations(phase and amplitude)as validation data.

Gräwe et al., in prep.

Sea surface salinity in the Wadden Sea (as seen in 200 m resolution model)

Personal communication Matias Duran Matute (NIOZ)

atmosphericchemistry

atmosphericphysics

benthic geoecology

benthic biogeochemistry

cohesivesediments

adaptiveecosystem& element

cycles

waves

riverdischarge

MOdular System for Shelf and Coasts (MOSSCo)

oceanphysics

oceanBGC

water physics

Major messagesThe 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