1. Towards Better Understanding of Eddy Variation Using SST Data: Application in the Northern Pacific Ocean
Changming “Charles” Dong
IGPP, University of California, Los Angeles
Yu Liu
SCSI, Chinese Academy of Science, GuangZhou, China
Acknowledgements: NASA PO Grant,
F. Nencioli, R. Lumpkin, M. Lankhorst, J. Vanzequez,
E. Armsrong, Y. Chao, J. McWillimas. D. Chen, and Y. Guan.

2. Outline Motivation Pseudo-Velocity Derived from SST Data Pseudo-EKE
Cohesive Eddies Product from REMSS SST
Summary

3. OBJECTIVE
Set up a global oceanic eddy data set by synthesizing available observational data
Observational data: SST, SSHA, global surface drifters, Argo data, and other in-situ data
Eddy Detection Tools
a. Nencioli and Dong et al (2009, JAOT)
(Automated Vector Geometry Eddy Detection)
b. Dong et al (2010, JAOT, submitted)
(Automated Loops Detection from Surface Drifters)
c. Dong et al (2010, IEEE-GRSL, submitted)
(Automated Eddy Detection Scheme from SST Data)

4. Example: Synthesis of SST, SSHA, and Drifters for an Eddy

5. Why we need a synthesis of these data: Abnormal Eddies

6. Application: Kuroshio Extension

7. SST-derived Pseudo-Velocity
A Sobel gradient operator is used to calculate SST gradients.
where A is the SST matrix divided by grid size
A pseudo-velocity vector V= (Ux,Uy), where
Ux= - Gy; Uy= Gx on the northern hemisphere
Ux= Gy; Uy= Gx on the southern hemisphere

8. Example: Pseudo-Velocity

9. More About Pseudo-Velocity
Where D is the vertical scale, α is the expansion coefficient
β is salt contraction coefficient.

10. Pseudo-EKE in the Northern Pacific Ocean

11. Comparable with EKE from SSHA

12. Compared with EKE from Global Surface Drifter Data

13. EKE Westward Propagation
U= 6 cm/s at 24~25 N

14. Eddy Identification Using SST-derived Pseudo-Velocity
Adapted from Dong et al (2010)

15. Example: Eddy Tracking

16. Application to REMSS SST (9km) in North Pacific Ocean

17. Statistical Analysis
REMSS SST
( )
AVISO SSHA
( )

18. Summary
Motivated by an objective to develop a global oceanic eddy data set by synthesizing available observational data
Pseudo-velocities derived from SST data are used for eddy Analysis
So far, we have finished KE region and NP. We will move on to the global ocean

19. Example: Eddy Automatic Track Using SST-derived Pseudo-Velocity