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.
Outline Motivation Pseudo-Velocity Derived from SST Data Pseudo-EKE Cohesive Eddies Product from REMSS SST Summary
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)
Example: Synthesis of SST, SSHA, and Drifters for an Eddy
Why we need a synthesis of these data: Abnormal Eddies
Application: Kuroshio Extension
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
Example: Pseudo-Velocity
More About Pseudo-Velocity Where D is the vertical scale, α is the expansion coefficient β is salt contraction coefficient.
Pseudo-EKE in the Northern Pacific Ocean
Comparable with EKE from SSHA
Compared with EKE from Global Surface Drifter Data
EKE Westward Propagation U= 6 cm/s at 24~25 N
Eddy Identification Using SST-derived Pseudo-Velocity Adapted from Dong et al (2010)
Example: Eddy Tracking
Application to REMSS SST (9km) in North Pacific Ocean
Statistical Analysis REMSS SST (2006-2008) AVISO SSHA (1993-2008)
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
Example: Eddy Automatic Track Using SST-derived Pseudo-Velocity