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Global ocean circulation patterns, adapted from Gilroy ECA presentation on ocean circulation. Website: gilroyeca.blogspot.com
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Components of the Climate System
• Atmosphere• Ocean
• Biosphere• Geosphere
Image from NASA
Atmosphere & Ocean Circulation
• Atmospheric Circulation– Depends on density
• Ocean Surface Circulation– Depends on the wind
• Deep Ocean Circulation– Depends on density
Why is Ocean Circulation Important?
• Transport ~ 20% of latitudinal heat– Equator to poles
• Transport nutrients and organisms
• Influences weather and climate
• Influences commerce
Temperature Structure of Ocean
thermocline
Ocean circulation patterns – Wind
Ocean circulation patterns – Surface Currents
Ocean Circulation
Winds and Currents• How fast? A few miles/hr (Gulf Stream
off of Miami = 4.5 mph)
• How much? Total water in ocean surface circulation = about 100 Amazon Rivers (20 million m3/s).
Atmosphere & Ocean Circulation
• Atmospheric Circulation– Depends on density
• Ocean Surface Circulation– Depends on the wind
• Deep Ocean Circulation– Depends on density
Sea Surface Temperature
http://www.ldeo.columbia.edu/dees/ees/climate/slides/sst_march.gif
Ocean Salinity
http://www.ldeo.columbia.edu/dees/ees/climate/slides/sal_march.gif• http://ingrid.ldgo.columbia.edu/
Temperature-Salinity (density) Diagram
Thermohaline circulation
The Great Conveyor The conveyor circulation transports heat to the North Atlantic. The sinking which takes place is susceptible to changes in surface salinity. If the surface of the North Atlantic gets too fresh, NADW won’t sink.
Global warming could increase melting of ice caps and sea ice, causing more fresh water to enter the Atlantic. Many models suggest that a shutdown of the conveyor would cause cooling over the North Atlantic and Europe. The conveyor has been off in the past during global cold periods, such as the last ice age and during the Younger Dryas. One hypothesis is that the shutdown of the conveyor, coupled with resultant atmospheric changes, is enough to throw the world into an ice age - or at least a cold snap.
Thermohaline Circulation
North Atlantic Deep Water
(NADW
15 million m3 of near surface water descend into the deep ocean each second.
Thermohaline Circulation - The Ocean Conveyor
Equatorial to polar heat transport and water flow
Ocean – Atmosphere Circulation
ENSOEl Niño/Southern Oscillation
3-7 year cycle of warming in E. Pacific
ENSO
El Niño/Southern Oscillation
NASA/Goddard Space Flight CenterScientific Visualization Studio
ENSO
El Niño/Southern Oscillation
http://svs.gsfc.nasa.gov/vis/a000000/a000200/a000287/index.htmlNASA/Goddard Space Flight CenterScientific Visualization Studio