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The formation of large-amplitude fingers in atmospheric vortices


Cosgrove, JM and Forbes, LK, The formation of large-amplitude fingers in atmospheric vortices, ANZIAM Journal, 57, (4) pp. 395-416. ISSN 1446-1811 (2016) [Refereed Article]

Copyright Statement

Copyright 2016 Australian Mathematical Society

DOI: doi:10.1017/S1446181115000243


Large-scale low-pressure systems in the atmosphere are occasionally observed to possess Kelvin–Helmholtz fingers, and an example is shown in this paper. However, these structures are hundreds of kilometres long, so that they are necessarily affected strongly by nonlinearity. They are evidently unstable and are observed to dissipate after a few days.

A model for this phenomenon is presented here, based on the usual f-plane equations of meteorology, assuming an atmosphere governed by the ideal gas law. Large-amplitude perturbations are accounted for, by retaining the equations in their nonlinear forms, and these are then solved numerically using a spectral method. Finger formation is modelled as an initial perturbation to the nth Fourier mode, and the numerical results show that the fingers grow in time, developing structures that depend on the particular mode. Results are presented and discussed, and are also compared with the predictions of the β-plane theory, in which changes of the Coriolis acceleration with latitude are included. An idealized vortex in the northern hemisphere is considered, but the results are at least in qualitative agreement with an observation of such systems in the southern hemisphere.

Item Details

Item Type:Refereed Article
Keywords:atmospheric vortices, pectral methods
Research Division:Mathematical Sciences
Research Group:Applied mathematics
Research Field:Theoretical and applied mechanics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the mathematical sciences
UTAS Author:Cosgrove, JM (Dr Jason Cosgrove)
UTAS Author:Forbes, LK (Professor Larry Forbes)
ID Code:114887
Year Published:2016
Web of Science® Times Cited:1
Deposited By:Mathematics and Physics
Deposited On:2017-03-01
Last Modified:2017-11-01

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