1. Eddy Detection from SSHA and SST Data
Changming Dong
Contributors: Francesco Nencioli, Yu Liu, Xiayan Lin

2. Outline SSHA Derived Geostrophic Velocity SST Derived Thermal Velocity
Apply “Velocity Geometry-based Automated
Eddy Detection Scheme” to the derived
velocity fields

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

4. Application: Kuroshio Extension

5. SSHA-derived Geostrophic Velocities

7. Eddies Detected from SSHA

8. SST-derived Thermal Velocity
Where D is the vertical scale, α is the expansion coefficient
β is salt contraction coefficient.

9. SST-derived Thermal 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

10. Example: Thermal Velocity

11. Pseudo-EKE in the Northern Pacific Ocean

12. Comparable with EKE from SSHA

13. Compared with EKE from Global Surface Drifter Data

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

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

16. Examples of Eddies Identified by SST

17. Example: Eddy Tracking

18. Eddy Distribution in Kuroshio Extension

19. Eddy Statistical Analysis

20. Example: Track Eddies Using SST-derived Thermal Velocity