Quantification and characterization of mesoscale eddies with different automatic identification algorithms

• Published in: Journal of coastal research Vol. 2; no. 65; p. 2077
• Main Authors: Viikmaee, Bert, Torsvik, Tomas
• Format: Journal Article
• Language: English
• Published: Fort Lauderdale Allen Press Inc 01.01.2013
• Subjects: Algorithms; Automation; Coastal; Coasts; Eddies; Flow characteristics; Fluid mechanics; Gulfs; Mesoscale phenomena; Ocean currents; Strength; ANE, Norway, Hordaland, Bergen; ANE, Baltic Sea, Finland Gulf; ANE, Norway, Raunefjord
• ISSN: 0749-0208; 1551-5036
• DOI: 10.2112/SI65-351

Automatic methods for detection of mesoscale eddies are usually based on either physical or geometrical flow characteristics. In this article, a hybrid method combining the strengths of the two different approaches is applied to the Eulerian velocity fields for two case studies: the Gulf of Finland (the Baltic Sea) and the Raunefjord and Vatlestraumen area south-west of Bergen, Norway. Velocity fields are investigated with a hybrid winding-angle method (HWA), where the Okubo-Weiss parameter is first used to detect potential eddies, and the winding-angle method is used locally within these regions to test the Okubo-Weiss result. In the Gulf of Finland, the HWA method results in a substantially reduced number of detected eddies compared with the Okubo-Weiss result, indicating that the Okubo-Weiss parameter severely overestimates the number of eddies. In Vatlestraumen, there was a better correspondence between results obtained by the HWA and the Okubo-Weiss methods. The HWA method requires careful analysis since more than one streamline may identify the same eddy structure.