Properties of the Geotail Plasma Sheet—Theory and Observation

  1. Joseph R. Kan,
  2. Thomas A. Potemra,
  3. Susumu Kokubun and
  4. Takesi Iijima
  1. C.J. Owen1,
  2. S. W. H. Cowley1 and
  3. I. G. Richardson2

Published Online: 19 MAR 2013

DOI: 10.1029/GM064p0215

Magnetospheric Substorms

Magnetospheric Substorms

How to Cite

Owen, C.J., Cowley, S. W. H. and Richardson, I. G. (1991) Properties of the Geotail Plasma Sheet—Theory and Observation, in Magnetospheric Substorms (eds J. R. Kan, T. A. Potemra, S. Kokubun and T. Iijima), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM064p0215

Author Information

  1. 1

    Blackett Laboratory, Imperial College, Prince Consort Road, London, SW7 2BZ, U.K.

  2. 2

    NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771, U.S.A.

Publication History

  1. Published Online: 19 MAR 2013
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780875900308

Online ISBN: 9781118663981



  • Magnetospheric substorms—Congresses


The properties of the plasma sheet formed by reconnection in the deep geomagnetic tail may be determined from consideration of the field and plasma stresses on the reconnected field lines threading a one-dimensional current sheet. In particular, we assume that the field tension is balanced by the anisotropic plasma pressure of the combined plasma populations flowing into, and out of, the tail current sheet, and calculate the speed of the outflowing plasma sheet needed to maintain this balance. Unlike previous models, we also include the possibility that the plasma is heated during its interaction with the current sheet, so that account can be taken of the diamagnetic depression of the plasma sheet magnetic field. The analysis also provides estimates of the thickness of the plasma sheet at a given downtail distance from the neutral line, and of the magnitude of the magnetic field component threading the current sheet. We briefly review differences in the plasma sheet properties expected if the flow were driven by a viscous transfer of momentum from the magnetosheath, and present an example of data which includes spacecraft encounters with both reconnection associated plasma sheet and viscously driven plasma sheet, indicating the need for both processes in explaining the configuration in the deep tail.