1. The Surface Currents Chapter 9

2. Surface Currents Wind driven Coriolis effect 45º

3. Surface Currents Ekman Spiral V. Walfrid Ekman ~100-150 m Ekman Transport 90 

4. Surface Currents Ocean Gyres

5. Surface Currents Geostrophic Flow

7. Pacific Ocean Currents North Equatorial North Pacific California Kuroshio Oyashio Alaska

8. Pacific Ocean Currents South Equatorial West Wind Drift Peru (Humbolt) East Australia Equatorial Countercurrent Cromwell

9. Atlantic Ocean Currents North Atlantic North Equatorial Gulf Stream Canary Florida Labrador East Greenland Norwegian

10. Atlantic Ocean Currents West Wind Drift South Equatorial Brazil Benguela

11. Indian Ocean Currents West Wind Drift South Equatorial West Australia Agulhas North Equatorial Equatorial Countercurrent

12. Arctic Ocean Currents Clockwise gyre Not centered on North Pole

13. Current Flow Current Speed 0.01 times average wind speed 0.1 – 0.5 m/sec Narrow straits Increase of speed Florida current Volume Sverdrups 1 Sverdrup = 1 million m 3 /sec

14. Current Flow Western Intensification Western Boundary Current Eastern Boundary Current

15. Eddies Meanders Surface or at depth Vary in size 10–100’s km in diameter Can alter surface flow pattern Retain properties

16. Eddies Gulf Stream Rotational speed 0.51 m/sec (1 knot) Diameter 325 km (200 mi) Reach bottom Abyssal storms

17. Convergence & Divergence

18. Langmuir Cells

20. Seasonal Zones

22. Global Currents

23. Milankovitch cycles 1. Shape of Earth’s orbit 100,000 years

24. Global Currents Milankovitch cycles 2. Tilt of Earth’s axis of rotation 41,000 years

25. Global Currents Milankovitch cycles 3. Circular revolution 23,000

26. Recent History of Climate Change Minimum solar radiation 23,000 years ago Maximum land ice & minimum water temps 17,000 years ago Return to high solar radiation 12,000 years ago

27. Recent History of Climate Change Younger Dryas event

28. Recent History of Climate Change

30. North Pacific Oscillations PDO Pacific Decadal Oscillation Yellow = Warm & dry Red = Cold & wet

31. North Atlantic Oscillations NAO Pools of warm & cool surface water 4 to 10 years

32. Measuring the Currents Highly sophisticated equipment:

33. Measuring the Currents

34. Current Meters

35. Measuring the Currents Doppler current meter Emits sound of known frequency Measures frequency of returning echoes