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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 33, issue 2
Ann. Geophys., 33, 217–224, 2015
https://doi.org/10.5194/angeo-33-217-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 33, 217–224, 2015
https://doi.org/10.5194/angeo-33-217-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 26 Feb 2015

Regular paper | 26 Feb 2015

Auroral vortex street formed by the magnetosphere–ionosphere coupling instability

Y. Hiraki Y. Hiraki
  • National Institute of Polar Research, Tokyo, Japan

Abstract. By performing three-dimensional magnetohydrodynamic simulations including Alfvén eigenmode perturbations most unstable to the ionospheric feedback effects, we examined the auroral vortex street that often appears just before substorm onset. We found that an initially placed arc splits, intensifies, and rapidly deforms into a vortex street. We also found that there is a critical convection electric field for growth of the Alfvén eigenmodes. The vortex street is shown to be a consequence of coupling between the magnetospheric Alfvén waves carrying field-aligned currents and the ionospheric density waves driven by Pedersen/Hall currents.

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By performing 3-D MHD simulations including Alfven eigenmode perturbations most unstable to the ionospheric feedback effects, we examined the auroral vortex street that often appears just before substorm onset. We found that an initially placed arc splits, intensifies, and rapidly deforms into a vortex street. We also found that there is a critical convection electric field. The vortex street is shown to be a consequence of M-I coupling between field-aligned currents and Pedersen/Hall currents.
By performing 3-D MHD simulations including Alfven eigenmode perturbations most unstable to the...
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