hans burchard baltic sea research institute warnemünde, germany [email protected]
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The invisible extremes: The dynamics of Baltic Sea inflow events. Hans Burchard Baltic Sea Research Institute Warnemünde, Germany [email protected]. Let us first have a look into the observed long-term surface salinity in the Central Baltic Sea. - PowerPoint PPT PresentationTRANSCRIPT
Hans Burchard
Baltic Sea Research Institute Warnemünde, Germany
The invisible extremes:The dynamics of Baltic Sea inflow events
Let us first have a lookinto the observed long-termsurface salinity in the Central Baltic Sea
Sea surface salinity in the Central Baltic Sea
Feistel et al., 2006
How to attribute this to a certain process ?
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
All inflows have to pass the Western Baltic Sea
Western Baltic Sea monitoring stations
Darss Sill: 19 m
+
Drogden Sill: 8 m
+MARNET (IOW/BSH)
Farvandsvæsenet
Arkona Sea: 48 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
baroclinic barotropic
Inflows over Drogden Sill (through Sound)
surface
bottom
Graphics: Frank Janssen (BSH)
Where does the Sound plume go ?
?
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• …
5 days
15 days
31 days
Sound lock-exchange experiment with GETM
Main plume goes via northof Kriegers Flak: Is this real ?
Bottom salinity: 8 – 25 psu
Burchard et al., OD, 2005.
Plume passing Kriegers Flak (Feb 2004)
Burchard et al., OD, 2005.
Current east [cm /s] / Salin ity [psu]
-35
-30
-25
-20
-15
-10
-5
0
Dep
th [m
]
-30-20-12-8-404812203040506070
12/05 01/06 02 /06 03/06 04/06 05 /06 06/06Current north [cm /s]
-35
-30
-25
-20
-15
-10
-5
0
Dep
th [m
]
-30-20-12-8-404812203040506070
12/05 01/06 02 /06 03/06 04/06 05 /06 06/06
Inflows north of Kriegers Flak
GETM Western Baltic Sea hindcast
GETM Western Baltic Sea hindcast
GETM Western Baltic Sea hindcast
Model validation: Darss Sill
Model derived monthly mean vertically integrated physically and numerically induced salinity variance decay
Physical mixing Numerical mixing
Burchard et al., 2007 (submitted), Burchard and Rennau, 2007 (submitted)
Nov 2005: Velocity structure of dense bottom current
Ship A:TL-ADCP
Ship B: Microstructure
View
1 km
Flow
Eastcomp.
Northcomp.
Can we explain the flow structure ?
Umlauf et al., GRL, 2007
GETM 2DV Slice Model: Transverse gravity current structure
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 contentsfrom entering to exiting the Baltic Sea.