Ocean currents and circulation


Talked about: Surface currents; Upwelling; Deep water currents

Wind-driven- upper 100m- creates friction at the surface- moves the top layer of water

Density-driven- caused by differences in salinity and temperature- very slow flows in deep water

The Gulf Stream: warm waters from the Carribbean moves along the eastern sea board- gradually dissipates into the North Atlantic drift- warms Europe. Can see "core rings". Part of a system of major oceanic circulation- most are wind driven currents- heat redistribution. 

Surface currents (top 50-100m) - only 10% ocean volume is involved. 

Wind(mostly trade winds and westerlies) drives the currents                                                    Ekman sprial- friction of wind over water+coriolis effect- net transport of water at 90o :depending on what hemisphere we are in. Nhemi- deflected to right. Shemi-deflected to left

Zonal wind systems- 3 circulation cells- caused by unequal heating of the Earth's surface-redistribute the Earths heat between the latitudes. Winds curve as they pass from one latitude to another. This causes westerlies and trade winds

Doldrums/horse latitudes- No wind. No wind-driven waves. Because winds diverge either side.

Gyres: Surface winds + Sun's heat + Coriolois effect + Gravity = Circulation of ocean surface

Clockwise in the N. hemisphere; Anti-clockwise in the S. Hemisphere. 

Ekman spiral also acts on surface water layer- upper layer wil drag underlying water with it but with less force. There is a diminution of speed downward. So surface currents move in a direction 45o to


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