Dynamics of dense overflows – detailed studies from the Western Baltic Sea Hans Burchard 1, Hans Ulrich Lass 1, Lars Umlauf 1, Karsten Bolding 2, Frank Janssen 3, Volker Mohrholz 1, Hannes Rennau 1 1. Baltic Sea Research Institute Warnemünde 2. Bolding & Burchard Hydrodynamics 3. Federal Maritime and Hydrographic Agency

Oder: Wie Jürgen Sellschopp das Modellieren schätzen lernte. Das kriegen die nie modelliert !

For the investigation of this problem, the international project cluster QuantAS (Quantification of water mass transformation processes in the Akona Sea) was set up. Graphics: Jan Donath (IOW) Photo: Frank Richter (Uni Rostock) © NDR Uli Lass (2002): „Wind turbine foundations may mix up dense bottom currents.“

Establishing the QuantAS Consortium in May Treppenabsatzfoto Nr. 257 …

Interessantes Projekt auch aus der Sicht der FWG. Wir könnten für Anfang 2004 mit Schiffszeit dabei sein.

Baltic Sea bathymetry Entire Baltic Belt Sea / Western Baltic

Western Baltic Sea: Bathymetry Darss Sill: 19 m + Drogden Sill: 8 m + MARNET (IOW/BSH) Farvandsvæsenet

baroclinic barotropic Inflows over Drogden Sill surface bottom Graphics: Frank Janssen (BSH)

Where does the Sound plume go ? ?

 x y U-V  Dense bottom currents: Balance between rotation, friction and pressure gradient

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 …

Lass die doch modellieren. Wir hocken lieber im Container und pflegen unsere Feldmessungen.

5 days 15 days 31 days Sound lock-exchange experiment with GETM Bottom salinity: 8 – 25 psu Kann das denn angehen ?

Searching for the plume

Plume coming down from the Sound (Feb‘ 2004)

Plume passing Kriegers Flak (Feb‘ 2004)

Profiles through plume north of Kriegers Flak (Feb‘ 2004)

Realistic simulation of the Februar 2004 plume Baltic Sea model: Baltic Sea MOM-3.1 model 3 nm horizontal resolution 77 vertical (geopotential) grid layers Meteo forcing from ECWMF Reanalysis Project ERA40 (until August 2002) German Weather Service Global Model with a resolution (from September 2002). Boundary conditions stored for elevation, temperature and salinity at 57 deg 30‘ N (Kattegat) and 16 deg 30‘ E (east of Bornholm Sea) Western Baltic Sea model: Sim-time: September 1, May 1, 2004 Forced by German Weather Service Local Model (resolution: 7 km and 3 hours) Lateral boundary conditions from Baltic Sea model Resolution: 1/2 nm in the horizontal, 50 general vertical coordinate layers Time step was 10 s for barotropic and 300 s for baroclinic mode.

Domain decomposition for Western Baltic Sea model

Bottom salinity in Arkona Sea

Salt transport across Drogden Sill

Model validation: Darss Sill

Model validation: Arkona Buoy

Feb section across Kriegers Flak

November 2005: More detailed QuantAS observations

Nov 2005: Velocity structure of dense bottom current Ship A: TL-ADCP Ship B: Microstructure View 1 km Flow East comp. North comp. Can we explain the flow structure ?

T2: Turbulence Measurements enhanced turbulence in down-welling region interfacial turbulence quiet core BBL Turbulence Ozmidov Scale: Ozmidov Scale Dissipation Rate

GETM 2DV Slice Model: Transverse gravity current structure

Na, Jürgen, war das nicht ne schöne Zeit, damals 03 – 07 ? Ach ja … und aus dem Modell konnte man ja so richtig was lernen … … dann kann ich ja in Rente gehen …