changming “charles” dong igpp, university of california, los angeles yu liu
DESCRIPTION
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, - PowerPoint PPT PresentationTRANSCRIPT
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Towards Better Understanding of Eddy Variation Using SST Data:
Application in the Northern Pacific Ocean
Changming “Charles” DongIGPP, University of California, Los Angeles
Yu LiuSCSI, 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.
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Outline
• Motivation• Pseudo-Velocity Derived from SST Data• Pseudo-EKE• Cohesive Eddies Product from REMSS SST• Summary
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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)
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Example: Synthesis of SST, SSHA, and Drifters for an Eddy
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Why we need a synthesis of these data: Abnormal Eddies
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Application: Kuroshio Extension
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SST-derived Pseudo-VelocityA 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 hemisphereUx= Gy; Uy= Gx on the southern hemisphere
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Example: Pseudo-Velocity
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More About Pseudo-Velocity
Where D is the vertical scale, α is the expansion coefficient β is salt contraction coefficient.
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Pseudo-EKE in the Northern Pacific Ocean
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Comparable with EKE from SSHA
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Compared with EKE from Global Surface Drifter Data
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EKE Westward Propagation
U= 6 cm/s at 24~25 N
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Eddy Identification Using SST-derived Pseudo-Velocity
Adapted from Dong et al (2010)
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Example: Eddy Tracking
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Application to REMSS SST (9km) in North Pacific Ocean
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Statistical Analysis
REMSS SST(2006-2008)
AVISO SSHA(1993-2008)
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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
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Example: Eddy Automatic Track Using SST-derived Pseudo-Velocity