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Summary: Vortices and Rossby waves in cylinder wakes on a parabolic -plane
observed by altimetric imaging velocimetry
Y. D. Afanasyev,1,2
P. B. Rhines,2
and E. G. Lindahl2
1
Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X7, Canada
2
University of Washington, Seattle, Washington 98125, USA
Received 6 December 2007; accepted 1 July 2008; published online 15 August 2008
Intense vortices in the wake of a circular cylinder are investigated in a rotating parabolic polar
-plane fluid. This system has a background potential vorticity PV field that supports Rossby
waves and causes vortices to migrate and radiate. A method for imaging rotating flows, which we
call "altimetric imaging velocimetry" is employed. Optical color coding of slopes of the free-surface
elevation field yields the pressure, geostrophic and gradient wind velocity, and potential vorticity
fields with very high spatial resolution, limited largely by the pixel resolution of the available
imaging sensors. Cylinder wakes on the polar -plane exhibit strikingly different regimes as it is
translated azimuthally, eastward or westward. Self-arrangement of vortices after the cylinder was
stopped drives an intense eastward jet formed by the rows of anticyclones and cyclones on its flanks.
In agreement with the idea of a PV staircase, this jet has a strong PV gradient at its center, while PV
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