Precipitation and nonlinear effects in geomagnetic field line resonancesournal of Geophysical Research: Space Physics, 108(A4), [pp

• Author(s) / Creator(s)

  • Tikhonchuk, V. T.
  • Prakash, M.
  • Rankin, Robert

• The structure of auroral arcs sustained by field line resonances (FLRs) is determined using a model that describes the interplay between ionospheric feedback, nonlinear, and dispersive effects in a curvilinear geomagnetic topology. The model includes modulation of Pedersen conductance by hundreds of eV electrons that precipitate in the ionosphere through the action of shear Alfven wave field-aligned currents (FACs). The competition between ionospheric feedback dissipation, wave dispersion, and nonlinearity results in large-amplitude, long-period oscillations of the FAC, and in emission of slow-moving small-scale secondary auroral arcs and density perturbations. Using observed values of nightside conductivities and realistic topology of geomagnetic field lines, we obtain FLRs with frequencies in the range of a few mHz, spatial scales up to several km near the ionosphere, and FAC amplitudes extending to tens of muA/m(2). Our model explains the excitation of structured auroral arcs in regions of low ionospheric conductance.

• Date created

  2003

• Subjects / Keywords

  • Acceleration
  • Small-Scale
  • Ionosphere
  • Electron-Energy
  • Density
  • Discrete Auroral Arcs
  • Shear Alfven Waves
  • Flux
  • Models
  • Dipolar Magnetosphere

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R34F1MZ7B

• License

  © 2003 American Geophysical Union. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.