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The motion of a singular vortex near an escarpment

Dunn, DC; McDonald, NR; Johnson, ER; (2001) The motion of a singular vortex near an escarpment. J FLUID MECH , 448 335 - 365. 10.1017/S0022112001006115. Green open access

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Abstract

McDonald (1998) has studied the motion of an intense, quasi-geostrophic, equivalent barotropic, singular vortex near an infinitely long escarpment. The present work considers the remaining cases of the motion of weak and moderate intensity singular vortices near an escarpment. First, the limit that the vortex is weak is studied using linear theory. For times which are short compared to the advective time scale associated with the vortex it is found that topographic waves propagate rapidly away from the vortex and have no leading-order influence on the vortex drift velocity. The vortex propagates parallel to the escarpment in the sense of its image in the escarpment. The mechanism for this motion is identified and is named the pseudoimage of the vortex. Large-time asymptotic results predict that vortices which move in the same direction as the topographic waves radiate non-decaying waves and drift slowly towards the escarpment in response to wave radiation. Vortices which move in the opposite direction to the topographic waves reach a steadily propagating state. Contour dynamics results reinforce the linear theory in the limit that the vortex is weak, and show that the linear theory is less robust for vortices which move counter to the topographic waves. Second, contour dynamics results for a moderate intensity vortex are given. It is shown that dipole formation is a generic feature of the motion of moderate intensity vortices and induces enhanced motion in the direction perpendicular to the escarpment.

Type: Article
Title: The motion of a singular vortex near an escarpment
Open access status: An open access version is available from UCL Discovery
DOI: 10.1017/S0022112001006115
Publisher version: http://dx.doi.org/10.1017/S0022112001006115
Language: English
Additional information: © 2001 Cambridge University Press
Keywords: GULF-STREAM RINGS, BETA-PLANE, TOPOGRAPHIC WAVES, COASTAL CURRENTS, INTENSE VORTEX, EVOLUTION, VORTICES, EDDY, DYNAMICS, FLOW
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Mathematics
URI: https://discovery.ucl.ac.uk/id/eprint/96847
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