Hans Burchard1,3, Frank Janssen2, Lars Umlauf1, Karsten Bolding3, and Hannes Rennau1

1. Baltic Sea Research Institute Warnemnde2. Bundesamt fr Seeschifffahrt und Hydrographie3. Bolding & Burchard Hydrodynamics

hans.burchard@io-warnemuende.de

Applications of the General Estuarine Transport Model (GETM) to the Western Baltic Sea

GETM is a 3D numerical model for estuarine,coastal and shelf sea hydrodynamics with applications to the

Tidal Elbe Wadden Sea Limfjord Lake of Geneva, Western Baltic Sea, North Sea Baltic Sea system

Present GETM characteristics ... physics ...

Solves three-dimensional primitive equations withhydrostatic and Boussinesq approximations.

Based on general vertical coordinates.

Options for Cartesian, spherical and curvilinear coordinates.

Fully baroclinic with tracer equations for salinity, temperature,suspended matter and ecosystem (from GOTM bio module).

Two-equation turbulence closure models with algebraicsecond-moment closures (from GOTM turbulence module).

Wetting and drying of intertidal flats is supported also inbaroclinic mode.

Present GETM characteristics ... numerics ...

Consistent explicit mode splitting into barotropic and baroclinic mode.

High-order positive-definite TVD advection schemes withdirectional split.

Choice of different schemes for internal pressure gradientcalculation.

Consistent treatment of zero-velocity bottom boundary condition for momentum.

Positive-definite conservative schemes for ecosystem processes (in GOTM-Bio module).

Motivation: wind farms in the Western Baltic Sea

Western Baltic Sea monitoring stationsDarss Sill: 19 m+Drogden Sill: 8 m+MARNET (IOW/BSH)Farvandsvsenet+Arkona Buoy: 48 m

baroclinicbarotropicInflows over Drogden SillsurfacebottomSource: Farvandsvsenet

Where does the Sound plume go ??

5 days15 days31 daysSound lock-exchange experiment with GETMMain plume goes via northof Kriegers Flak: Is this real ?Bottom salinity: 8 25 psu

Plume passing Kriegers Flak (Feb 2004)

GETM Western Baltic Sea hindcast

GETM Western Baltic Sea hindcast

Model validation: Darss Sill

Model validation: Drogden Sill

Model validation: Arkona Buoy

Section acrossKriegers Flak

Model derived annual mean mixing in Western Baltic Sea

Nov 2005: Velocity structure of dense bottom currentEastcomp.Northcomp.Can we explain the flow structure ?

Western Baltic Sea conclusions:

Density currents in Western Baltic Sea are highly variable,show a complex transverse structure and induce substantial natural transports and mixing.

For evaluating additional anthropogenic mixing due tooffshore structures on these currents, proper parameterisations need to be foundand inserted into 3D model (QuantAS-Off).

Multiple bridges and wind farms may result incumulative mixing effects.

RV Gauss leaving Warnemnde for its last research cruise

GETM 2DV Slice Model: Transverse gravity current structure

GETM Western Baltic Sea hindcast