Feb18_09_OceanCirculation2

Feb18_09_OceanCirculation2 - Ocean Circulation Ocean...

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Ocean Circulation
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Ocean Circulation *Wind-driven circulation Near-surface circulation directly driven by the wind. *Thermohaline circulation Deep water circulation, driven by changing the density of sea water. Note that driving forces for both types of circulation are located at the sea surface!
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Surface Currents What are some effects of ocean currents? Transfer heat from tropical to polar regions Influence weather and climate Distribute nutrients and scatter organisms Surface currents are driven by wind: Most of Earth’s surface wind energy is concentrated in the easterlies and westerlies. Due to the forces of gravity, the Coriolis effect, solar energy, and winds, water often moves in a circular pattern called a gyre .
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Subtropical Gyre Subtropical (mid-latitude) ocean is dominated by subtropical gyre . Maintained by the subtropical high pressure system and its associated wind (westerly wind at mid-latitudes and easterly trade wind in the tropics). Higher sea level in the middle of a basin (resulting from Ekman transport ). The resulting geostrophic current flows clockwise (counterclockwise) in the northern (southern) hemisphere
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Surface winds in August In the subtropics, winds are westerly in the poleward region and easterly in the equatorward region!
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Surface Currents Are Driven by the Winds (below) A combination of four forces surface winds, the sun’s heat, the Coriolis effect, and gravity circulates the ocean surface clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere, forming gyres. (above) The North Atlantic gyre, a series of four interconnecting currents with different flow characteristics and temperatures.
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Ocean Circulation
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The powerful western boundary currents flow along the western boundaries of ocean basins in both hemispheres. Antarctic Circumpolar Current (ACC) : Steady unimpeded westerly wind blowing north of the Antarctic Continent drives ACC which carries the largest transport of any currents. This current is also a geostrophic current responding to the cooling near the Antarctic. It is deep (all the way to the bottom). Major surface currents in the world
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This note was uploaded on 10/07/2011 for the course OCS 1005 taught by Professor Condrey during the Spring '08 term at LSU.

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Feb18_09_OceanCirculation2 - Ocean Circulation Ocean...

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