Ocean Structure and Circulation

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Ocean ModelTemperature

De

pth

Surface

Deeper

WarmerColder

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Ocean Model

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“Warm” shallow surface layer

Cold deep layer

Transition Zone

Ocean Model

4How do the layers form?

SurfaceLayer

DeepWater

TransitionZone

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Homogeneous Ocean

Taking the Temperature

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ConductivityTemperature Depth

CTD

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Ocean Temperature

Deep Water

• 90% of the total volume of ocean is this cold, deep water. •At depths greater than 1000m, temperature is approximately 4ºC (even in the tropics!!).

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Why do layers form?

Thermocline = Temperature Change

Surface Layer

Transition Zone

7

Mass per unit volume

Lighter1000 kg/m3

Denser1020-1028 kg/m3

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Because of Density

Lighter100 kg/m3

Denser19,300 kg/m3

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8

Ocean Density

Surface Layer

Deep Water

• Seawater density is controlled by Temperature and Salinity

•In the ocean, Temperature has a greater effect on density

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Pycnocline = Density ChangePycnocline Transition Zone

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SurfaceLayer

DeepWater

BoundaryTransitionZone

Thermocline & Pycnocline

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SurfaceLayer

DeepWater

Boundary

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Mixed

Warmed and lit by sun

Photosynthesis

Cold, Dark, No Photosynthesis

Less Nutrients

, More Nutrients

Surface Ocean

• Warm• Lit by the sun• Has photosynthesis• Less nutrients

Deep Ocean

• Cold• Dark• No photosynthesis• More Nutrients

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Summary