1. Leibniz Institute for Baltic Sea Research
A baroclinic 3D
model for the
entire Wadden Sea
Hans Burchard
Leibniz Institute for Baltic Sea Research
Warnemünde, Germany
1: IOW, 2: HZG, 3: NIOZ, 4: Uni Eindhoven,
5: ICBM, 6: IFREMER
JGR, 2016.

2. Motivation: Wind straining in tidal inlet
tides
buoyancy
gradient
wind
Exploiting a validated 3D model of the Sylt-Rømø-Bight tidal inlet …
Purkiani et al. (2015, 2016)

3. Estuarine circulation
Warming Precipitation
Land
Ocean
Downward surface buoyancy flux
Sea bed
Weak tidal mixing: vertically stratified
Wind straining
River
Estuarine circulation
Strong tidal mixing: horizontally stratified

4. Motivation: Wind straining in tidal inlet
Up-channel wind
Down-channel wind
Longitudinal buoyancy gradient
classical
circulation
exchange flow
Exchange flow intensity
1 Feb 2008
10 Feb 2008
20 Feb 2008
Exchange flow intensity M: z
inverse
circulation
 M=u0
<u>
-u0 u0
Purkiani et al. (2016)

5. Motivation: Wind straining in tidal inlet
buoyancy gradient
wind stress
February 2008
strong wind
March 2008
medium wind
How does this look like in other inlets?
April 2008
exchange flow intensity
weak wind
down up-
channel
Purkiani et al. (2016)

6. Model of entire Wadden Sea: Setup
General Estuarine Transport Model
Fully baroclinic
k-epsilon turbulence closure
Cartesian, Dx=Dy=200m
30 vertical sigma layers
Atmospheric forcing: DWD
Runtime
Gräwe et al. (2016)

7. Model of entire Wadden Sea: Forcing
Wind speed
Wind direction
Precipitation
Ijssel runoff
Elbe runoff
Gräwe et al. (2016)

8. Model of entire Wadden Sea: SST and SSS
Gräwe et al. (2016)

9. Model of entire Wadden Sea: Validation of M4 tide
Gräwe et al. (2016)

10. Model of entire Wadden Sea: Validation of T & S
Gräwe et al. (2016)

11. ? Model of entire Wadden Sea: Validation of tidal transports
Gräwe et al. (2016)

12. Model of entire Wadden Sea: Wind versus buoyancy gradient
classical inverse
classical inverse
inverse classical
classical inverse
down up
down up
down up
Gräwe et al. (2016)

13. Conclusions
This first baroclinic model for the entire Wadden Sea allows
to investigate differences in dynamics between different regions.
All inlets react differently to buoyancy gradient and wind stress forcing.
Residual flows strongly depend on local bathymetry.
For some regions, 200m is certainly a too coarse resolution. Need for an
unstructured grid model for the entire Wadden Sea with Dx<30m locally?
We should start using this model for investigating sediment dynamics and
biogeochemistry of the entire Wadden Sea.