Chapt09_Ocean_Circ

Chapt09_Ocean_Circ - Ocean Circulation Ocean Chapter 9...

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Ocean Circulation Ocean Circulation Chapter 9
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Geostrophic Currents Geostrophic Currents As water moves it is constantly  deflected by the Coriolis Effect   This effect pushes water into a  hill in the center of the gyre. It is about 1 meter high in the  center of the Atlantic Nevertheless, it IS a hill, and  water runs downhill.  This is shown by the arrow  labeled 'gravity' in the diagram.
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There is a balance between  the pushing in of the Coriolis  effect, and the flowing out by  gravity (which deflects to the  right in the N. Hem.), which  keeps the whole thing  spinning as a  geostrophic  current So, once the winds get the  gyres moving, they are  somewhat self-perpetuating.
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Gulf Stream Gulf Stream Best-studied of the  ocean currents The Gulf Stream, like  streams on land,  wobbles.  These wobbles are  known as  eddies It wobbles outward, as  shown in diagram  a and wobbles inward, as  shown in diagram  b
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The wobbles often wobble so far, that a whole  gob of Gulf Stream water pinches off from the  stream and heads south (diagram a) or north  (diagram b).  These are known as  rings . This is yet  another way by which warmth is sent from the  Gulf Stream to the northeast coast of North  America.  Notice the rings spin. 
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The outward wobble (a)  takes cold water (shown in  blue) from off the coast of  New England (or northeast  Canada) and sends it to  the center of the North  Atlantic gyre (an area  known as the Sargasso  Sea). The inward wobble (b)  takes warm water (shown  in red) and sends it up to  the coast of New England. 
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The Ekman Spiral The Ekman Spiral When wind blows over the surface of the  water, we expect it to drag the water along  with it, in the same direction.  However, it doesn't.  You may have noticed that the Trade Winds,  which move the Equatorial Currents, are  blowing diagonally across the map, but the  water is moving horizontally. What's going on? The Coriolis Effect, again! 
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The Trade Winds blow from the northeast in  the northern hemisphere.  The water they drag along is deflected to the  right.  Now this water is moving is a given direction,  and it drags the water just beneath it with it.  The water just beneath the surface is also  deflected to the right. THIS water drags water beneath IT, which is 
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Chapt09_Ocean_Circ - Ocean Circulation Ocean Chapter 9...

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