1. Hans Burchard, Elisabeth Schulz and Henk Schuttelaars
Impact of estuarine convergence on residual circulation
in tidally energetic estuaries and inlets
Hans Burchard, Elisabeth Schulz and Henk Schuttelaars

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

3. Width-averaged tidal inlet model (2DV, x-z)
shelf sea
land
island
inter-tidal
island
Burchard et al. (in prep.)

4. Width-averaged tidal inlet model: Net precipitation
Burchard et al. (in prep.)

5. Width-averaged tidal inlet model: no buoyancy flux
What is this?
Burchard et al. (in prep.)

6. The physics of estuarine convergencez
flood
ebb x x u
Estuarine convergence adds
an ebb tendency to the flow.
Ebb tendency (surface-enhanced)
+ pressure gradient drives exchange flow.
(Ianniello, 1979)

7. Constant eddy viscosity (1DV)
A: cross-sectional area
Red: classical
H&R65 solution
Burchard, Schulz & Schuttelaars, GRL 2014

8. Variable eddy viscosity (1DV) Tidal straining circulation
MacCready & Geyer (2010) after Jay & Musiak (1994)

9. Variable eddy viscosity (1DV)
Non-dimensional parameters of the model:
Convergence number:
Simpson number:
Unsteadiness number:
Burchard, Schulz & Schuttelaars, GRL 2014

10. Variable eddy viscosity simulations (1DV)
Decomposition of residual flow profiles according to Burchard & Hetland (2010)
Convergence reduces or even reverts tidal straining circulation.
Burchard, Schulz & Schuttelaars, GRL 2014

11. Parameter space study Colour code: intensity of estuarine circulation
Burchard, Schulz & Schuttelaars, GRL 2014

12. Maybe this even exists in nature.
Conclusion
Channel convergence may reduce estuarine circulation for weak buoyancy forcing.
Maybe this even exists in nature.