![Page 1: Hans Burchard Baltic Sea Research Institute Warnemünde, Germany hans.burchard@io-warnemuende.de](https://reader036.vdocuments.us/reader036/viewer/2022081603/56813b2c550346895da3f37a/html5/thumbnails/1.jpg)
Hans Burchard
Baltic Sea Research Institute Warnemünde, Germany
The invisible extremes:The dynamics of Baltic Sea inflow events
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Let us first have a lookinto the observed long-termsurface salinity in the Central Baltic Sea
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Sea surface salinity in the Central Baltic Sea
Feistel et al., 2006
How to attribute this to a certain process ?
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Bottom salinity in the Central Baltic Sea
Feistel et al., 2006
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A century of salinity in the Central Baltic Sea
Graphics: Courtesy to Markus Meier
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All inflows have to pass the Western Baltic Sea
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Western Baltic Sea monitoring stations
Darss Sill: 19 m
+
Drogden Sill: 8 m
+MARNET (IOW/BSH)
Farvandsvæsenet
Arkona Sea: 48 m
+
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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)
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Baltic Inflows over Darss Sill: the year 2003
Major barotropic inflow
Strong baroclinic inflow
Source: IOW
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baroclinic barotropic
Inflows over Drogden Sill (through Sound)
surface
bottom
Graphics: Frank Janssen (BSH)
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Where does the Sound plume go ?
?
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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• …
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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.
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Plume passing Kriegers Flak (Feb 2004)
Burchard et al., OD, 2005.
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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
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GETM Western Baltic Sea hindcast
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GETM Western Baltic Sea hindcast
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GETM Western Baltic Sea hindcast
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Model validation: Darss Sill
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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)
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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
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GETM 2DV Slice Model: Transverse gravity current structure
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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.