Polar Cap Current Systems

  1. Thomas A. Potemra
  1. E. Friis-Christensen

Published Online: 21 MAR 2013

DOI: 10.1029/GM028p0086

Magnetospheric Currents

Magnetospheric Currents

How to Cite

Friis-Christensen, E. (1984) Polar Cap Current Systems, in Magnetospheric Currents (ed T. A. Potemra), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM028p0086

Author Information

  1. Division of Geophysics, Danish Meteorological Institute

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


It is the purpose of this paper to review the present understanding of polar cap current systems.

During the last decade there has been an increasing interest in the very high latitude currents particularly in the polar cap and the polar cusp. These regions are connected to the boundaries of the magnetosphere and are therefore showing immediate response to variations in the solar wind, especially in the interplanetary magnetic field. Ground based measurements as well as polar orbiting satellites have revealed a lot of features of the distribution of currents and electric fields in the polar cap. Individual observations have demonstrated the high degree of variability in the polar cap and the polar cusp. Statistical investigations have revealed some of the general and repeatable features of the polar cap currents. A number of primary current systems, ionospheric and field-aligned, have been defined. The relationship between the different current systems, in particular near the dayside cusp, is still not fully understood because this region is characterized by rapid temporal and spatial variations. The elucidation of these variations demands a lot of simultaneous observations. Different interpretations of the polar cusp currents and their relationship to the auroral electrojets and to the Birkeland currents are discussed.