Vortex streets driven by sheared flow and applications to black aurora

P. K. Shukla, G. T. Birk, R. Bingham

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

Black aurora often exhibits the signature of vortex structures. In this paper, it is proposed that pseudo-three-dimensional drift-like electrostatic modes can play a very important role in those phenomena. Employing a two-fluid model, we derive a set of nonlinear equations governing the dynamics of long wavelength inertial convective cells and coupled drift-acoustic waves in the presence of geomagnetic field-aligned plasma flows. It is shown that free energy stored in the latter can cause purely growing and oscillatory instabilities in the auroral ionosphere. The threshold conditions as well as expressions for the linear growth rates are presented. Furthermore, it is found that possible stationary solutions of the nonlinear equations can be represented in the form of vortex structures. It is, therefore, likely that the nonlinear low-frequency electrostatic modes, as described here, may possibly account for the coherent vortex structures within black aurora, as they are often observed during the late recovery phase of a substorm.
LanguageEnglish
Pages671-674
Number of pages4
JournalGeophysical Research Letters
Volume22
Issue number6
DOIs
Publication statusPublished - 15 Mar 1995

Fingerprint

vortex streets
aurora
vortex
vortices
nonlinear equations
electrostatics
two fluid models
acoustic wave
geomagnetism
magnetohydrodynamic flow
geomagnetic field
ionospheres
ionosphere
recovery
free energy
signatures
low frequencies
wavelength
plasma
thresholds

Keywords

  • dynamics
  • evolution
  • flows
  • instability
  • plasma
  • waves
  • ionosphere
  • structure

Cite this

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Vortex streets driven by sheared flow and applications to black aurora. / Shukla, P. K.; Birk, G. T.; Bingham, R.

In: Geophysical Research Letters, Vol. 22, No. 6, 15.03.1995, p. 671-674.

Research output: Contribution to journalArticle

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AU - Shukla, P. K.

AU - Birk, G. T.

AU - Bingham, R.

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