1. Surface circulation Deep ocean circulation

2. Surface currents General pattern
Gyres created by wind and modified by Coriolis effect
Water moves horizontally
Selected other currents

3. Trade Winds (grey) and
Westerlies (green)
create gyres (purple)

5. Gyres General circular flow of surface currents
Western boundary currents (intensified)
Eastern boundary currents
Equatorial currents

7. Ekman transport Driven by winds Modified by Coriolis
Currents veer 90 degrees to the right or left of the wind (depending on hemisphere)
Water piles up in center of gyres

8. Ekman transport – note direction of wind over water and direction of net transport of top 100 meters of water

9. Ekman transport (version 2) - note arrows spiraling down – progressively smaller and changing direction down to 100 meters depth
kman Transport

10. Geostrophic circulation
Driven by gravity
Modified by Coriolis effect
Water flows down away from center of hill in center of gyre, but bends due to Coriolis

11. Geostrophic circulation imagine hill of water at center of gyre

12. Upwelling and downwelling along a coast

13. El Nino circulation – note position of warm and cold surface water
Top – “normal”
Middle – El Nino
Bottom – La Nina

14. Deep ocean circulation
THERMOHALINE (temp and salinity)
Density driven
Formation of distinct water masses
Sinking at poles and movement toward equator
Different from surface ocean circulation

15. Deep ocean circulation - simplified

16. Conveyor belt model of deep ocean circulation

17. Closer look at Gulf Stream
Flows like a river with meanders
Meanders pinch off and become rings
Warm core eddies
Cold core eddies