Hans Burchard, Frank Janssen, Hans Ulrich Lass, Volker Mohrholz, Hannes Rennau,

and Lars Umlauf

Leibniz Institute for Baltic Sea Research Warnemünde, Germany

Internal technical support: Toralf Heene, Günter Plüschke, Dietmar Rüss, Ingo

Schuffenhauer

External scientific collaboration: Lars Arneborg, Karsten Bolding, Volker Fiekas,

Frank Gerdes, Michaela Knoll, Hartmut Prandke, Jürgen Sellschopp

Status of the QuantAS-Off regional scale dynamical studies

Kriegers Flak

Motivation: wind farms in the Western Baltic Sea

Western Baltic Sea monitoring stations

Darss Sill: 19 m

+

Drogden Sill: 8 m

+MARNET (IOW/BSH)

Farvandsvæsenet

baroclinic barotropic

Inflows over Drogden Sill

surface

bottom

Source: Farvandsvæsenet

Where does the Sound plume go ?

?

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., 2005

Plume passing Kriegers Flak (Feb 2004)

Burchard et al., 2005

For more details, seeSellschopp et al., 2006

sum m er heating

overflow soverflow s

outflow s

seasonal therm ocline

w inter coo ling

win

ter

sum

mer

in terna lm ix ing

perm anent ha locline

uplift

in terleaving

in terna lwave m ixing

bottomcurrententra inm ent

surface wavem ix ing

boundarym ix ing

convectiveentra inm ent

shear-inducedentrainm ent

differentia ladvection

riverrunoff

w ind stress

coasta lupw elling

sun

Baltic Sea vertical mixing processes

How would offshore wind farm foundations affect this ?

Reissmann et al., 2007

Role of vertical mixing for the Baltic Sea ecosystem

GETM Western Baltic Sea hindcast

Burchard et al, 2007

GETM Western Baltic Sea hindcast

GETM Western Baltic Sea hindcast

Model validation: Darss Sill

Burchard et al, 2007

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., 2007

Arneborg et al., 2007: Entrainment laws for each location

GETM 2DV Slice Model: Transverse gravity current structure

Umlauf et al., in prep.

volker.mohrholz@io-warnemuende.de

QuantAS – Quantification of water mass transformations in the Arkona Sea

11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5

Longitude [deg]

54.2

54.4

54.6

54.8

55.0

55.2

55.4

55.6

55.8

56.0

56.2La

titud

e [d

eg] Skanör

Viken

Oresound

KFSE

KFN

BGE

DS

AB

FB

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Depth[m ]

BornholmBasin

ArkonaBasin

Pom eranian Bight

DarssSill

Fehm arn Belt

Rønne Bank

Bornholm-gatt

Drogden Sill

KriegersFlak

Adlergrund

Oderbank

Time series stations

Mohrholz et al., in prep.

QuantAS – Quantification of water mass transformations in the Arkona Sea

volker.mohrholz@io-warnemuende.de

Moored devices

SeabirdMicrocat

SeabirdMicrocat

SeabirdMicrocat

SeabirdMicrocat

SeabirdMicrocat

SeabirdSeacat

/////////////////////////////////////////////////////////////////////////////

31

34

36

21

26

Anchor 200kg

200kg

MC

MC

MC

MC

MC

10

Depth(m)

8

Seac

at No

.

ø108. 5cm

M2005-12XT6000

BENTHO

S875

Bouyancy

BenthosReleaser

Quantas

Ropebox

//////////////////////////////////////////////////////////////////////////////////////////////

TR6000

ADCP

Leinenbox

40

35

Releaser

TR6000

25

10

Depth (m)

0

80m Groundrope

Seacat

3 0

Seac

at N

o.

Seacat Seac

at N

o.

500 Bouyancy

20kg

Seacat

Seacat Seac

at N

o.Se

acat

No.

Argos-transponder

30kg

PLÜ.

Bouyancy

08.03.2004

Kriegers Flak North Kriegers Flak South

Mohrholz et al., in prep.

QuantAS – Quantification of water mass transformations in the Arkona Sea

volker.mohrholz@io-warnemuende.de

Salinity time series

-30

-20

-10

0

-20

0

-10

0

Salinity - Kriegers Flak North

Salinity - Drogden Sill

Salinity - Darss Sill

Jan

05

Feb

05M

rz 0

5

Apr 0

5

Mai

05

Jun

05

Jul 0

5

Aug

05

Sep

05

Okt

05

Nov

05

Dez

05

Jan

06

Feb

06M

rz 0

6

Apr 0

6

Mai

06

Jun

06

Jul 0

6

Aug

06

Sep

06

Okt

06

Nov

06

Dez

06

5678910111213141618202224

Mohrholz et al., in prep.

QuantAS – Quantification of water mass transformations in the Arkona Sea

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19D istance [nm ]

Log10(D iss ip . ra te [W /kg ]) (contour) / S igm aT [kg/m ³] (iso lines)

-40

-30

-20

-10

0

Dep

th [m

]

55 .09 55.10 55 .11 55.12 55 .13 55 .14 55.15 55.16La titude [deg ]

Log10(D iss ip . ra te [W /kg ]) (contour) / S igm aT [kg/m ³] (isolines)

-40

-30

-20

-10

0

Dep

th [m

]

- 9

- 8

- 7

- 6

- 5

- 4

- 3

55.09 55 .10 55.11 55.12 55.13 55 .14 55.15 55.16

C urrent velocity east [m /s] (contour) / S igm aT [kg /m ³] (iso lines)

-40

-30

-20

-10

0

Dep

th [m

]

-0 .30-0 .20-0 .12-0 .08-0 .040.000.040.080.120.200.300.400.500.600.70

Cross channel transect30.01.2006 07:50 - 10:49 UTC

Along channel transect30.01.2006 11:58 - 22:39 UTC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

C urrent ve locity east [m /s] (contour) / S igm aT [kg/m ³] (iso lines)

-40

-30

-20

-10

0

Dep

th [m

]

volker.mohrholz@io-warnemuende.de

Inflowing plume north of Kriegers Flak

Mohrholz et al., in prep.

Hydrography at Bornholmsgat

QUANTAS – ADP structure function approach

55 .24 55.26 55.28 55.30 55.32 55.34 55.36 55 .38 55.40 55.42

Salin ity [PS U ]

-60

-40

-20

0

Dep

th [m

]

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

55 .24 55.26 55.28 55.30 55.32 55.34 55.36 55 .38 55.40 55.42

La titude [degN ]

log E ps ilon [W /kg] (color) - S igm a-t [kg /m ³] (contou r)

-60

-40

-20

0

Dep

th [m

]

- 9

- 8

- 7

- 6

- 5

- 4

- 3

14 .0 14.2 14.4 14 .6 14.8 15.0

Longitude [deg E ]

55.2

55.3

55.4

55.5

Latit

ude

[deg

N]

Mohrholz et al., in prep.

Transverse structure in Bornholm Channel

Reissmann et al., 2007

Model derived monthly mean vertically integrated physically and numerically induced salinity mixing

Physical mixing Numerical mixing

Burchard et al., 2007; Burchard and Rennau, 2007; Rennau et al., in prep.

10.82 10.84 10.86 10.88 10.9 10.92 10.94 10.96 10.9855.295

55.3

55.305

55.31

55.315

55.32

55.325

55.33

Longitude [Degree East]

Latit

ude

[Deg

ree

Nor

th]

Scanfish Tracks with R/V Prof. A. Penck close to the western GBL in April 2006

-800 -600 -400 -200 0 200 400 600 80020

25

30

salin

ity p

su

-800 -600 -400 -200 0 200 400 60015

20

25

salin

ity p

suDistance from the western GBL [m]

-800 -600 -400 -200 0 200 400 60015

20

25

salin

ity p

su

depth: 8 m

depth: 4 m

depth: 4.4 m

4 Apr 19 UTC; Fr = 0.67

5 Apr 13 UTC, Fr = 1.2

5 Apr 14 UTC; Fr = 1.2

Signature of piles

Current

Salz

geha

ltTe

mpe

ratu

r

Mixing by bridge

Mixing at the piles of the Western Great Belt Bridge

2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 440018

20

22

24

26

28

salin

ity p

su

40/06/07 Scanfish 0004 03

2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 44003.4

3.6

3.8

4

4.2

4.4

Distance [m]

t090

C [d

eg C

]

40/06/07 Scanfish 0004 03

depth: 4.5 m

5 April 12 UTC; Fr = 1.2

Lass et al., submitted

CTD chain tows at Western Great Belt Bridge

Lass et al., submitted

upstream downstream

Basic parameterisation for friction due to structures in water

Additional production of turbulence:

Friction coefficient:

QuantAS-IOW-Publications• Burchard, H., H.U. Lass, V. Mohrholz, L. Umlauf, J. Sellschopp, V. Fiekas, K.

Bolding, and L. Arneborg, "Dynamics of medium-intensity dense water plumes in the Arkona Sea", Western Baltic Sea, Ocean Dynamics, 55, 391-402, 2005.

• Sellschopp, J., L. Arneborg, M. Knoll, V. Fiekas, F. Gerdes, H. Burchard, H. U. Lass, V. Mohrholz, L. Umlauf, "Direct observations of a medium-intensity inflow into the Baltic Sea", Cont. Shelf Res., 26, 2393-2414, 2006.

• Arneborg, L., V. Fiekas, L. Umlauf, and H. Burchard, "Gravity current dynamics and entrainment - a process study based on observations in the Arkona Sea", J. Phys. Oceanogr., 37, 2094-2113, 2007.

• Umlauf, L., L. Arneborg, H. Burchard, V. Fiekas, H.U. Lass, V. Mohrholz, and H. Prandke, The transverse structure of turbulence in a rotating gravity current, Geophys. Res. Lett., 34, L08601, doi:10.1029/2007GL029521, 2007.

• Mohrholz, V., H. Prandke and H. U. Lass, Estimation of TKE dissipation rates in dense bottom plumes using a Pulse Coherent Acoustic Doppler Profiler (PC-ADP) - Structure function approach, J. Mar. Sys., accepted for publication.

• Burchard, H., F. Janssen, K. Bolding, L. Umlauf, and H. Rennau, Model simulations of dense bottom currents in the Western Baltic Sea, Cont. Shelf Res., accepted for publication.

• Burchard, H., and H. Rennau, Comparative quantification of physically and numerically induced mixing in ocean models, Ocean Modelling, accepted for publication.

• Reissmann, J., H. Burchard, R. Feistel, E. Hagen, H.U. Lass, V. Mohrholz, G. Nausch, L. Umlauf, and G. Wieczorek, State-of-the-art review on vertical mixing in the Baltic Sea and consequences for eutrophication, Progr. Oceanogr., accepted for publication.

• Lass, H.U., V. Mohrholz, M. Knoll, and H. Prandke, "On the impact of a pile on a moving stratified flow", Cont. Shelf Res., submitted.

Conclusions:

The inflow dynamics of the Arkona Sea are far more complex than assumed before.

Specifically the role of Earth rotation for entrainment had been underestimated before.

Next steps:

Calibration of the friction parameterisation by means of the lab experiments,the RANS experiments and the Great Belt Bridge field observations.

Various numerical experiments without and with the parameterisation ofdifferent wind farm locations and abundances in the Arkona Sea.

Evaluation of the wind farm effects and general recommendations for futurewind farm locations.