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The invisible extremes: The dynamics of Baltic Sea inflow events. Hans Burchard Baltic Sea Research Institute Warnemünde, Germany hans.burchard@io-warnemuende.de. Let us first have a look into the observed long-term surface salinity in the Central Baltic Sea.
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The invisible extremes: The dynamics of Baltic Sea inflow events Hans Burchard Baltic Sea Research Institute Warnemünde, Germany hans.burchard@io-warnemuende.de
Let us first have a look into the observed long-term surface salinity in the Central Baltic Sea
Sea surface salinity in the Central Baltic Sea How to attribute this to a certain process ? Feistel et al., 2006
Bottom salinity in the Central Baltic Sea Feistel et al., 2006
A century of salinity in the Central Baltic Sea Graphics: Courtesy to Markus Meier
Western Baltic Sea monitoring stations Farvandsvæsenet Drogden Sill: 8 m + MARNET (IOW/BSH) + + Arkona Sea: 48 m Darss Sill: 19 m
Three types of Baltic Sea inflow events: Major Baltic inflows – barotropic (wind driven) Strong Baltic inflows – baroclinic (density driven) Medium Baltic inflows – mixed (typically through Sound)
Baltic Inflows over Darss Sill: the year 2003 Major barotropic inflow Strong baroclinic inflow Source: IOW
Inflows over Drogden Sill (through Sound) baroclinic barotropic surface bottom Graphics: Frank Janssen (BSH)
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 • …
Sound lock-exchange experiment with GETM 5 days 15 days 31 days Bottom salinity: 8 – 25 psu Main plume goes via north of Kriegers Flak: Is this real ? Burchard et al., OD, 2005.
Plume passing Kriegers Flak (Feb 2004) Burchard et al., OD, 2005.
Numerical mixing Model derived monthly mean vertically integrated physically and numerically induced salinity variance decay Physical mixing Burchard et al., 2007 (submitted), Burchard and Rennau, 2007 (submitted)
Ship A:TL-ADCP Ship B: Microstructure Flow View 1 km Nov 2005: Velocity structure of dense bottom current Can we explain the flow structure ? East comp. North comp. Umlauf et al., GRL, 2007
Conclusion: Even after decades of intensive Baltic Sea research, there are still many miracles to be understood. The major physical process question is: How does the Baltic Sea overturn work ? This includes the understanding of the entire pathway (in time and space) of water and its contents from entering to exiting the Baltic Sea.