Precipitation-evaporation driven estuarine circulation (PEEC)in tidal inlet systems

Hans Burchard1, Henk M. Schuttelaars2, Johannes Becherer1

1. Leibniz Institute for Baltic Sea Research, Warnemünde, Germany2. Delft University of Technology, The Netherlands

?

Is there residual thermohaline circulationin tidal inlet systems such as the Wadden Sea?

Warming Precipitation

Weak tidal mixing: vertically stratified

Strong tidal mixing: horizontally stratified

Land

Thermohaline estuarine circulation

Sea bed

River?

The Wadden Sea circulation in a nutshell:

Sea

2DV numerical experiment using GETM:

Net precipita

tion

Net evaporation

E = P

Global ocean: Spatially inhomogeneous surface buoyancy fluxes plus internal mixing leads to global overturning circulation. Wadden Sea: Spatially homogenous surface buoyancy fluxes over sloping bathymetry plus tidal mixing should lead to residual overturning circulation.

Geometry

Wadden Sea density thermohaline gradient climatology

Burchard et al. (JPO, 2008)

Burchard et al. (JPO, 2008)

Becherer et al. (GRL, 2011)

With density gradients

Without density gradients

Observations of straining due to net precipitation

Impact of net precipitation on sediment transport

Conclusion:Other than in tidal estuaries, the estuarine circulation in tidal inlet systems such as the Wadden Sea may betruly thermohaline, mainly driven by surface buoyancy fluxes, with a significant impact on sediment dynamics.

Density (HW-LW)

Salinity (HW-LW) Temperature (HW-LW)

3D GETM simulation:

www.rapid.ac.uk