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Laboratory experiments on mesoscale vortices colliding with an island chain

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dc.contributor.author Tanabe, Aya
dc.contributor.author Cenedese, Claudia
dc.date.accessioned 2010-07-13T14:36:20Z
dc.date.available 2010-07-13T14:36:20Z
dc.date.issued 2008-04-17
dc.identifier.citation Journal of Geophysical Research 113 (2008): C04022 en_US
dc.identifier.uri http://hdl.handle.net/1912/3747
dc.description Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C04022, doi:10.1029/2007JC004322. en_US
dc.description.abstract The present laboratory study investigates the behavior of a self-propagating barotropic cyclonic vortex colliding perpendicularly with aligned circular cylinders and determines the condition for a vortex to bifurcate and split into multiple vortices and/or to generate dipoles downstream of the cylinders. During the experiments, four parameters were varied: G, the gap width between the cylinders; d, the diameter of the incident vortex; Y dis , a parameter expressing the initial vortex positions; and D isl , the total length of the “middle” island. It has been observed that as long as 0.1 < G/d ≤ 0.4, the vortex fluid was funneled between two cylinders at one of the gaps and a dipole generally formed, much like water ejected from a circular nozzle generates a dipole ring. After the dipole formed, the cyclonic part of the dipole became dominant and self propagated away from the cylinders. Furthermore, in some experiments having 0.2 < D isl /d ≤ 0.5, after a weak dipole formed, the remnant of the original vortex moved zonally “south.” When the remnant of the vortex came in contact with a new cylinder, fluid peeled off the outer edge of the vortex and a so-called “streamer” went around the cylinder in a counterclockwise direction. Under the right conditions, this fluid formed a new cyclonic vortex in the wake of the cylinder, causing bifurcation of the original vortex into two vortices, as observed in previous studies. In general, independently of the configurations and Y dis , the number of cyclonic vortices downstream of the cylinders was one, either originating from the dipole or generated by the bifurcation of the original vortex. The vortex center position, radius, and circulation, before and after the interaction, were computed from its velocity field. It was found that for 0.1 < G/d ≤ 0.4, intense vortices experienced greater amplitude loss than weak vortices. The formation of both a dominant cyclone and an anticyclone (i.e., a dipole) downstream of the aligned cylinders, representing an island chain, is in agreement with recent oceanic observations of North Brazil Current (NBC) rings interacting with the Lesser Antilles in the Eastern Caribbean Sea. Since the passages of the Lesser Antilles have values of 0.07 ≤ G/d ≤ 0.3, the oceanic observations might be explained by the experimental results reported in this paper. en_US
dc.description.sponsorship A.T. was supported by GFD Summer Fellowship 2005. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.uri http://dx.doi.org/10.1029/2007JC004322
dc.subject Mesoscale vortices en_US
dc.subject Island chain en_US
dc.subject Laboratory experiments en_US
dc.title Laboratory experiments on mesoscale vortices colliding with an island chain en_US
dc.type Article en_US
dc.identifier.doi 10.1029/2007JC004322


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