Deep Ocean Circulation
http://nssdc.gsfc.nasa.gov/planetary/image/earth_day.jpg
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Effect of Solar Radiation on Sea
Surface Temperature
Sunlight
Modified image from Windows to the Universe, http://www.windows.ucar.edu
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Sea Surface Temperature
oceanworld.tamu.edu
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Surface Currents
Sea to Air
Heat Transfer
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Deep Ocean Currents Driven by
Density of Seawater
hawaiianphotos.net
melindawebster.com
What effects water density?
• Colder water
Denser (to 4°C)
• Saltier water
Denser
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Deep water forms when:
http://oceanexplorer.noaa.gov/
● Surface water
flows to the poles
and gets colder
● When seawater
freezes it leaves
salt behind,
increasing salinity
● Water becomes
denser and sinks
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Modeling cold salty water sinking
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Global Conveyor Belt
Sinking Cold,
Salty Water
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Courtesy NASA/JPL-Caltech
http://sealevel.jpl.nasa.gov/index.html
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Global Conveyor Belt
Thermohaline Circulation
– Thermo = temperature
– Haline = salinity
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Why is thermohaline circulation important?
• Major influence
on climate
• Transfers heat
from equator to
poles
• Nutrient cycling
• Brings oxygen to
deep ocean
organisms
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O2
Warmed and lit by sun
PRODUCED in surface ocean
Mixed with atmosphere
(oxygen)
Mixed
Surface
Ocean
Boundary
Deep
Ocean
O2
Photosynthesis
O2
O
2
Less Nutrients
Cold, Dark, No Photosynthesis, More Nutrients
Oxygen (O2) USED
O2
O2
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How will global climate change
affect thermohaline circulation?
• Melting of sea ice
• Increased
precipitation
informify.com
Decrease in
salinity
May alter
thermohaline
circulation
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