Magnetospheric Topology of Fields and Currents

  1. Thomas A. Potemra
  1. Walter J. Heikkila

Published Online: 21 MAR 2013

DOI: 10.1029/GM028p0208

Magnetospheric Currents

Magnetospheric Currents

How to Cite

Heikkila, W. J. (1984) Magnetospheric Topology of Fields and Currents, in Magnetospheric Currents (ed T. A. Potemra), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM028p0208

Author Information

  1. Center for Space Sciences, The University of Texas at Dallas, P.O. Box 688, Richardson, TX 75080

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1984

ISBN Information

Print ISBN: 9780875900551

Online ISBN: 9781118664131



  • Magnetospheric currents—Congresses;
  • Plasma instabilities—Congresses


This paper proceeds from the view that the existence of the boundary layer inside the magnetopause is crucial to the plasma physics of the magnetosphere. The boundary layer flow is so massive that it can generate its own electric field for continued anti-sunward flow. At very great distances (some 100 to 200 Re downstream from the earth) the dawn and dusk boundary layers become joined together, and the magnetotail is essentially just boundary layer plasma, on closed magnetic field lines. Evidence concerning closed field lines in the polar cap is the migration of breakup auroras near midnight during the recovery phase. This poleward migration is here interpreted as the ionospheric footprint of the tailward expulsion of a plasmoid from the plasma sheet through the distant magnetotail; the auroral forms move poleward to 75°–80° latitude or even higher, indicating that there is a wide band of closed field lines above the nightside auroral oval. The region of open field lines is smaller than previously thought. The electric field must have some dramatic changes, some in consort with changes of the magnetic field. These changes involve charge separation as well as induction through time-dependence of the magnetic field. Field aligned currents arise due to both of these sources. Our suggestion of how region 1 and 2 currents arise is generally in agreement with others. However, there is still another current, which we name as the region 0 current system at the boundary between open and closed magnetic field lines. The region 0 current may be weak; it is in parallel with the magnetopause current over the lobes of the magnetotail; together, they are the closure current of part of the region 1 current system (region 2 provides the remainder). The main conclusion of these conjectures is that auroral phenomena along the oval are mostly the result of the boundary layer, a form of viscous interaction.