Ekman Transport: water flows at an angle to the prevailing wind direction

• Each successive layer is dragged by the surface layer
• Lower velocity in the deeper layers deflects them more due to coriolis force
• Net flow across the Ekman Spiral approaches 90 degrees to wind direction
• Spiralling to the right in the N. Hemisphere and to the left in the S. Hemisphere

In coastal areas:

• Upwelling : net Ekman transport of surface water away from land
• Downwelling: net Ekman transport of surface water toward the land

Surface ocean circulation : driven by winds

• North and South Equatorial currents -west ward moving trade winds

Boundary currents - effect of land masses; deflection of westward moving equatorial currents poleward, parallel to a coast line.

• N. Atlantic - Gulf Stream; N. Pacific - Kuroshio
• S. Atlantic - Brazil current; Indian Ocean- Mozambique
• S. Pacific - E. Australian current

• Boundary currents change direction when they reach westerlies
  • In the Northern Hemisphere:
    • Kuroshio turns east ward as the N. Pacific Current
    • Gulf stream turns NE as the N. Atlantic current
  • In the Soutern Hemisphere:
    • Brazil, E. Australian and the Mozambique become the Antarctic Circum-polar current flowing east and circling the earth at 60 S.
• Gyres: major circular moving bodies of water as the boundary currents get deflected by winds and coriolis forces
  • 5 gyres, two each in Pacific and Atlantic and one in the Indian Ocean
  • Clockwise in the N. Hemisphere and anti-clockwise in S. Hemisphere
• Motion of cool water from high latitude
  • In the S. Hemisphere:
    • Humboldt current off west coast of S. America
    • Beneguela current off west coast of Africa
  • In the N. Hemisphere:
    • Cool high latitude waters off w. coast of Alaska and Greenland

Deep water circulation: Thermohaline circulation

• Antarctic bottom water
• North Atlantic deepwater
• Intermediate waters- Mediterranean
• Pacific - dominated by antarctic deep water
• The Global Ocean Conveyor system

Interactions between the oceans and the atmosphere

• Oceans as heat reservoirs due to high heat capacity of water
• Heat absorption and redistribution
  • Warming of cold regions - Gulf Stream
  • Cooling of warm regions - Coast of California, S. America
  
  
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