Internal Shear Layers in Auroral Dynamics

  1. T. E. Moore,
  2. J. H. Waite Jr.,
  3. T. W. Moorehead and
  4. W. B. Hanson
  1. W. Lotko1 and
  2. C. G. Schultz2

Published Online: 18 MAR 2013

DOI: 10.1029/GM044p0121

Modeling Magnetospheric Plasma

Modeling Magnetospheric Plasma

How to Cite

Lotko, W. and Schultz, C. G. (1988) Internal Shear Layers in Auroral Dynamics, in Modeling Magnetospheric Plasma (eds T. E. Moore, J. H. Waite, T. W. Moorehead and W. B. Hanson), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM044p0121

Author Information

  1. 1

    Dartmouth College, Hanover, New Hampshire 03755

  2. 2

    Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780875900704

Online ISBN: 9781118664414

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Keywords:

  • Space plasmas—Mathematical models;
  • Magnetosphere—Mathematical models;
  • Ionosphere—Mathematical models

Summary

An important part of the magnetosphere-ionosphere interaction takes place in narrow layers where the vorticity is locally enhanced and where the internal dynamics are largely influenced by effects of viscosity, field-aligned potential drops, and ionospheric friction. Within these layers the ionospheric impression of magnetospheric electric fields and field-aligned currents is selectively filtered and dissipated and, depending on the magnetic field mapping, can evolve anisotropically. The processes by which energy is transported in the layer also depend sensitively on the wave number spectrum of the electric fields that exist within it. These effects are described in the context of a two-dimensional, time-dependent model which is characterized by two intrinsic parameters: a flux tube anisotropy factor and an effective Hartmann number that measures the ratio of (ionospheric) resistive friction to (magnetospheric) viscous friction. Illustrative numerical calculations indicate that turbulent magnetospheric flows may organize into either relatively isotropic eddies or striated shear layers depending on the values of these parameters. The possibility of using the model (or improved versions of it) to interpret observations of two-dimensional mesoscale turbulence at auroral latitudes is discussed briefly.