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…