1

Regionale Ozeanographie

08 – Randmeere des Atlantischen Ozeans

Literatur:

Tomczak, M. and S.Godfrey (2002): Regional Oceanography: An Introduction.

Kostenloser download unterhttp://www.es.flinders.edu.au/~mattom/regoc/pdfversion.html Denmark Strait Currents

Mediterranean seas

Tomczak & Godfrey, 2005

2

Arctic Mediterranean bathymetry

Tomczak & Godfrey, 2005

Arctic meteorology

Tomczak & Godfrey, 2005

3

Arctic surface circulation

Tomczak & Godfrey, 2005

Sea ice cover

Tomczak & Godfrey, 2005

4

Ice coverage

2006

2007L. Kaleschke

Spreading of Atlantic Water,cyclonic wind forcing

Freshwater input

Cooling

Circulation & forcing

5

Arctic hydrography

Tomczak & Godfrey, 2005

Arctic hydrography

Tomczak & Godfrey, 2005

6

Arctic hydrography

Tomczak & Godfrey, 2005

Atlantic Water inflow

Hansen & Østerhus, 2000

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Atlantic Water in the Arctic

Tomczak & Godfrey, 2005

Background stratification

Prater, 2005

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Convection

θ S

σ

Rudels et al., 2000

Shelf slope convection

Dense water formation on shelvessinking down continental slopesentrainment of ambient water

Open ocean convection

Dense mixed layerpenetrative & non-penetrative plumes

entrainment of ambient watereddy formation

Marshall and Schott, 1999

Convection

Temp

Salz

Mixed layer deepening Air-sea fluxes

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Overflows

Hansen & Østerhus, 2000

Faroe Bank Channel overflow

Hansen & Østerhus, 2000

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Faroe Bank Channel overflow

Hansen & Østerhus, 2000

Denmark Strait overflow

Tomczak & Godfrey, 2005

Denmark Strait Currents

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Exchange across the GSR

PW

OV

AW

OV

Observed overflowtransports

DSO – Denmark StraitFBC – Faroe Bank

Channel

Temperature distribution

AW – Atlantic Water ~ 8 SvPW – Polar Water ~ 2 SvOV – Overflow Water ~ 6 Sv

FBC large scale mixing

Temp – Sal diagramme

WestCentralChannel

observations

AW

LSW

OW

OW Overflow WaterLSW Labrador Sea Water

AW Atlantic Water

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Faroe Bank Channel: Downstream flow

Eddy formation downstreamof channel’s exit, 3-5 d

Mixing at interface

Rotating table plume experimentstrong density contrast

Plume temperature in-situ

Diapycnal mixingrequires Kz ~10-2 m2/s

inflow

13

Stirring through eddies

Rotating table plume experimentweak density contrast

time

Bottom temperature

cold

warm

cold

Mooring data in plume

Faroe Bank Channel: Downstream mixing

10,000 1,000 100 10−1

−0.5

0

0.5

1

1.5

2

2.5

3Faroe Bank Channel overflow plume

distance [km]

temperature DegCdepth metreskin. energy (cm/s)2

0

1000

2000

3000

100

300

500

700

sill Iceland

Ch. Gibbs FZ

Equator this study

• Strong vertical shear in the channel

• Cross circulation in the channel

• Stirring through eddies AH ~ 102 m2/s

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Overflow movie

Labrador Sea

Tomczak & Godfrey, 2005

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Great salinity anomaly

Prater, 2005

Labrador Sea convection

Prater, 2005

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Labrador Sea convection

Prater, 2005

Downstream flow

Vertical distribution of temperature at ~60°N

Polar outflowWarm Inflow

Labrador ScotlandDeep outflows

Deep flows

Shallow flows

McCartney, 1997

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Northern AMOCWind

Arctic Mediterranean presently providesabout 2/3 to NADW at a very stable pace

Antarctic intermediate water

Tomczak & Godfrey, 2005

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Antarctic Bottom Water

Prater, 2005

Antarctic bottom water

Tomczak & Godfrey, 2005

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Eurafrican Mediterranean

Tomczak & Godfrey, 2005

Surface circulation

Tomczak & Godfrey, 2005

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Salinity section

Tomczak & Godfrey, 2005

Hydrography

Tomczak & Godfrey, 2005

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Mediterranean outflow Water

Tomczak & Godfrey, 2005

Mediterranean eddies

Richardson et al. (2000)

Serra, 2004

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Mediterranean eddies

Tomczak & Godfrey, 2005

American Mediterranean Sea

Tomczak & Godfrey, 2005

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Water renewal

Tomczak & Godfrey, 2005

Surface circulation

Tomczak & Godfrey, 2005

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Atlantic overturning circulation

Tomczak & Godfrey, 2005

Ocean circulation (cartoon)

cooling heating coolingprecipitation evaporation precipitation

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South Atlantic

Tomczak & Godfrey, 2005

Averaging climatological data