1. COMPARISON OF COASTAL CURRENTS FROM HF RADAR AND ADCP DATA
OC3570
LCDR Kim, KC ROKN
16 SEP 2003

2. PURPOSE
to examine the Horizontal Pattern of Shear observed on July 21
to examine the Relationship of CODAR data with ADCP data
to describe the Surface Current Circulation in Monterey Bay

3. Fundamental Issues on Naval OPS
Littoral Ocean
complicated coastline and complex bathymetry
winds, waves, and currents interact with the boundaries on much smaller space and time scales
Conventional measurement techniques are limited
military operations in Littoral Ocean
Mine OPS
Amphibious OPS
LOTS(Logistics over the Shore) OPS

4. HF RD Introduction Usage Measuring Currents
to measure sfc current Vel fields near the coast
to provide a higher resolution in space
Measuring Currents
Resonant Bragg Scattering: amplifies the scattered signal directed toward the reciever

5. Doppler Shift: how to calculate the surface currents
When electromagnetic waves interact with a mobile surface, the surface velocity induces a shift
 = 2 u/ c
Simple situation: a current constant with depth travelling in the direction of wave propagation
cw = cpw + U
under the assumption U<<cpw
cw = cpw + cw(k)
: original frequency
u: vel of the TGT
c: speed of light
c: wave’s apparent speed
cp: wave’s phase speed
U (z): horizontal current vel profile

6. Sample HF Doppler spectrum showing Bragg resonant peaks from
approaching and receding waves.

9. DATA Collection *

10. DATA Collection(Cont’)B
Time series on A and B A B

11. DATA Collection(Cont’)
Data for Time series on A and B
Total Data Points
Missing Data Points
Mean
STD
Time Gap
U Vel. At HF RD 52 9
-0.57 cm/s
9.68
60 min
V Vel. At HF RD
-0.56 cm/s
9.5
U Vel. At 15m
104
0.57 cm/s
4.62
30 min
U Vel. At 23m
1.22 cm/s
5.08
U Vel. At 31m
2.14 cm/s
4.81
V Vel. At 15m
1.56 cm/s
6.78
V Vel. At 23m
2.41 cm/s
5.61
V Vel. At 31m
2.91 cm/s
4.36

12. Bathymetry of the Canyon

13. LEG I

14. Depth: 15m
Depth: 25m
Depth: 75m
Depth: 125m

15. Depth: 175m
Depth: 225m
Depth: 275m
Depth: 325m

16. Time Series at the Head of Canyon

17. HF RD
ADCP Depth: 15m
ADCP Depth: 23m
ADCP Depth: 31m

18. Total U Vel at 15m
Total V Vel at 15m
Corr.: 0.29
Corr.:
Total U Vel at 23m
Total V Vel at 23m
Corr.:
Corr.:
Total U Vel at 31m
Total V Vel at 31m
Corr.:
Corr.:

19. UA Vel at 15m
VA Vel at 15m
Corr.:
Corr.:
UA Vel at 23m
VA Vel at 23m
Corr.:
Corr.:
UA Vel at 31m
VA Vel at 31m
Corr.:
Corr.:

20. UB Vel at 15m
VB Vel at 15m
Corr.:
Corr.:
UB Vel at 23m
VB Vel at 23m
Corr.:
Corr.:
UB Vel at 31m
VB Vel at 31m
Corr.:
Corr.:

22. 260400

23. 261800

24. 270400

25. Possible Reason?

26. SFC Current Circulation
In MTRY Bay( )

28. SFC Current Circulation
In MTRY Bay( )

30. Conclusion U Velocity has Low correlation but V has High.
More correlation on location B(Further off the coast) than A in both U and V component.
Further experiment with a Longer Time series and more stations needed for the better understanding this process.

31. REFERENCES
Special Issue on High Frequency Radars for Coastal Oceanography, Oceanography, Vol. 10, No
Lorell A. Meadows, High Frequency Radar Measurements of Friction Velocity in the Marine Boundary Layer

32. QUESTION?