1. Combination of oceanographic data with wind data acquired during the cruise to try to draw conclusions on wind stress, Ekman transport and Ekman layer for selected zones in the area of operations
LT Guillermo Coll

2. Outline Motivation Theoretical background Observations
Results/Conclusions

3. Motivation
Try to see if theoretical processes can be observed in practice
Ekman layer, Ekman spiral, Ekman transport were studied in OC3240 (Ocean Dynamics I)
Steady wind conditions in certain areas of the cruise seem adequate

4. Theoretical Background
wind u
Momentum is imparted to the water by the wind stress and transported down by the vertical friction

5. Theoretical Background
There are two distinct components of the flow:
Geostrophic component
Ekman component
caused by friction
caused by the pressure gradient

6. Theoretical Background
Ekman equations
The amplitude of Ekman velocity exponentially decreases with depth
Direction of Ekman velocity rotates clockwise with depth

7. Theoretical Background
Ekman layer = Frictional influence layer. Depth at which the current forms 180 degrees with respect to the wind stress

8. Observations

9. Observations
WIND LEG-I

10. Observations
WIND LEG-I

11. Observations

12. Observations

13. Observations

14. Observations
WIND LEG-II

15. Observations

16. Observations
08/ UTC to
08/ UTC

17. Observations Current data obtained from R/V Point Sur ADCP.
u,v components measured at mean depth of 8m bins, starting from z=-15 m.
Data used from 6 upper bins.
(z=-19 m to z= -67 m).
Data downloaded every 5 min.

18. Results
In general, computed directions in the upper layer don’t show clear relation with wind stress direction.

19. Results
SHIP MOVING

20. Results
SHIP MOVING
Large standard deviations of u and v when the ship is moving

21. Results
SHIP MOVING

22. Direction Correlation Coefficient Matrix (08/02 0253-0755 UTC)
Results
SHIP MOVING
Direction Correlation Coefficient Matrix (08/ UTC)
Depth

23. Speed Correlation Coefficient Matrix (08/02 0253-0755 UTC)
Results
SHIP MOVING
Speed Correlation Coefficient Matrix (08/ UTC)
Depth

24. Results
SHIP AT STATION

25. Results SHIP AT STATION
Large standard deviations of u and v when the ship is at station

26. Results
SHIP AT STATION

27. Direction Correlation Coefficient Matrix (08/03 0259- 0545 UTC)
Results
SHIP AT STATION
Direction Correlation Coefficient Matrix (08/ UTC)
Depth

28. Speed Correlation Coefficient Matrix (08/03 0259- 0545 UTC)
Results
SHIP AT STATION
Speed Correlation Coefficient Matrix (08/ UTC)
Depth

29. Conclusions

30. Conclusions
No clear results where obtained about the relation between wind stress and currents in the upper layers.

31. Conclusions
No clear results where obtained about the relation between wind stress and currents in the upper layers.
A long time series is needed to average out current forcing due to tidal currents, internal waves, etc..

32. Conclusions
No clear results where obtained about the relation between wind stress and currents in the upper layers.
A long time series is needed to average out current forcing due to tidal currents, internal waves, etc..
Locally, some clockwise current shear was observed and there was good correlation between the current direction change in the upper layers.

33. Conclusions
No clear results where obtained about the relation between wind stress and currents in the upper layers.
A long time series is needed to average out current forcing due to tidal currents, internal waves, etc..
Locally, some clockwise current shear was observed and there was good correlation between the current direction change in the upper layers.
On a moving ship, ADCP current data might not be accurate enough for this research.

34. Conclusions
No clear results where obtained about the relation between wind stress and currents in the upper layers.
A long time series is needed to average out current forcing due to tidal currents, internal waves, etc..
Locally, some clockwise current shear was observed and there was good correlation between the current direction change in the upper layers.
On a moving ship, ADCP current data might not be accurate enough for this research.
Geostrophic data are needed to complete the study.

35. QUESTIONS?