1. Generalized Surface Circulation

2. Nansen’s Trip in the “frozen” Fram (1893-96)

3. Nansen’s Observations about Surface Currents

4. Ekman’s Force Balance
Current
Coriolis
Wind
Walfred Ekman
Drag
Current direction is to the right of the wind in N. Hemisphere

5. Ekman’s Three Force Vector Balance (in the northern hemisphere)
Wind Stress Force
Current Direction (not a force)
Coriolis Force (always perpendicular to the Current direction)
Frictional Force (always opposes direction of current)
Resulting Force
(the combination of the Coriolis Force and Frictional Force yields a Resulting force that is equal to and in opposite direction to the Wind Stress Force)

6. Ekman Spiral

7. Ekman Spiral Observations (surface layer in the N. Atlantic)
Wind Direction
Measured Current Directions and Velocities at 5, 10, 15 and 25 m depths

8. Generalized Pattern of Surface Winds
July
Arrows indicate direction of Ekman Transport
January

9. Map of Sea Surface Height (ARGO floats) (in dynamic cms relative to 1500 dbar)
Sea surface height range is ~300cm or 3 m.

10. Pressure
P = g ρ Z

11. Horizontal Pressure Gradients

12. Geostrophic Force Balance

13. Geostrophic Current Flow around a dome of pressure

14. Sea Surface Height Anomaly (dynamic centimeters)
(dynamic height is relative to 1000dbar)
(Arrows represent direction of geostrophic current flow)

15. Barotropic and Baroclinic Conditions
Size of arrow indicates speed of current

16. Depth Profile of Typical Geostrophic Current Velocity

17. Cross Section of Density in Pacific Ocean
What meridional trend in sea surface height would be implied under baroclinic conditions?

18. Phosphate Distribution in Surface Ocean

19. Chlorophyll in the Surface Ocean

20. Gulf Stream
Franklin’s map of Gulf Stream and ‘gyre’ in 1785

21. Temperature and Salinity Sections across the Gulf Stream
Pot. Temp.
Temperature and Salinity Sections across the Gulf Stream
Salinity

22. Current Velocities in the Region of the Gulf Stream
White= northward flow
Blue = southward flow

23. Sea Surface Temperatures and Major Warm and Cool Currents

24. Gulf Stream Rings picture of SST observed from satellites
Gulf Stream Ring Movie

25. Temperature Anomalies of Gulf Stream Rings