Satellite Observations of Fine Scale Structure in Auroral Field-Aligned Current System

  1. C. T. Russell,
  2. E. R. Priest and
  3. L. C. Lee
  1. E. M. Dubinin

Published Online: 21 MAR 2013

DOI: 10.1029/GM058p0555

Physics of Magnetic Flux Ropes

Physics of Magnetic Flux Ropes

How to Cite

Dubinin, E. M. (1990) Satellite Observations of Fine Scale Structure in Auroral Field-Aligned Current System, in Physics of Magnetic Flux Ropes (eds C. T. Russell, E. R. Priest and L. C. Lee), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM058p0555

Author Information

  1. Space Research Institute, Academy of Sciences, USSR

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1990

ISBN Information

Print ISBN: 9780875900261

Online ISBN: 9781118663868

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Keywords:

  • Solar photosphere;
  • Magnetic flux;
  • Astrophysics

Summary

Strong disturbances (ΔE ∼100 mV/m and ΔB ∼100 nT) are often observed on a background of large-scale auroral quasi-stationary field-aligned current structures. The small scales have been difficult to understand due to the lack of such fine-scale current structures in the outer magnetosphere. The ratio between the amplitudes of the mutually perpendicular components of the electric and magnetic fields for small-scale structures (ℓ ≤ 20 km) at altitudes ∼1000 km turns out to be VA/C. This amplitude corresponds to the nonstationary shear Alfven waves. Bursts of precipitating electrons accompany these waves. The fine scale structure of the fields is analyzed. The structure of the fields resembles convective plasma vortices and peculiar magnetic islands that correspond to filamentary field-aligned current tubes. Phase shifts between perturbations of the electric and magnetic fields are often observed. Interference effects can be responsible for these phase shifts. Among small-scale events the localized disturbances, Alfven vortices are elucidated. Beside them wide zones (100–1000 km) of Alfven wave turbulence are often observed. The properties of this turbulence resemble the properties of the usual two-dimensional hydrodynamic turbulence (power law spectra; vortex structure of the disturbances at different spectral intervals). It is shown that the effects of the nonlinear interaction of shear Alfven waves with finite amplitudes can be responsible for some of the observed peculiarities.