Isee 3 Magnetic Field Observations in the Mgnetotail: Implications for Reconnection

  1. Edward W. Hones Jr.
  1. G. L. Siscoe1,
  2. D. G. Sibeck1,
  3. J. A. Slavin2,
  4. E. J. Smith2,
  5. B. T. Tsurutani2 and
  6. D. E. Jones3

Published Online: 19 MAR 2013

DOI: 10.1029/GM030p0240

Magnetic Reconnection in Space and Laboratory Plasmas

Magnetic Reconnection in Space and Laboratory Plasmas

How to Cite

Siscoe, G. L., Sibeck, D. G., Slavin, J. A., Smith, E. J., Tsurutani, B. T. and Jones, D. E. (1984) Isee 3 Magnetic Field Observations in the Mgnetotail: Implications for Reconnection, in Magnetic Reconnection in Space and Laboratory Plasmas (ed E. W. Hones), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM030p0240

Author Information

  1. 1

    Department of Atmospheric Sciences, Ucla, Los Angeles, CA 90024

  2. 2

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109

  3. 3

    Physics Department, Brigham Young University, Provo, UT 84600

Publication History

  1. Published Online: 19 MAR 2013
  2. Published Print: 1 JAN 1984

ISBN Information

Print ISBN: 9780875900582

Online ISBN: 9781118664223



  • Histograms;
  • Magnetic field observations;
  • Magnetometer measurements;
  • Magnetotail;
  • Plasma sheet


ISEE 3 explored the magnetotail to a distance of 220 RE during its first two tail orbits. The characteristic cross-sectional structure of the tail near the earth was recognizable to apogee. The field strength in the lobes and the Bz component in the plasma sheet decreased systematically with distance. The frequency of occurrence of negative Bz Increased with distance. Beyond 210 RE, the average Bz was slightly negative. The observations suggest the existence of an x-type neutral line located on average near 200 RE.

In addition to the systematic variations with distance, three types of transient events were recorded. The first type, which the spacecraft encountered on more than 30 occasions, is a discrete magnetic structure of 5 to 20 minutes duration distinguished by strong diamagnetism, a bipolar north-to-south Bz signature, hot plasma, high energy particles and increased wave activity. These events occur during intervals of geomagnetic activity. Hones has Identified these structures as tailward moving plasmoids produced by reconnection within the tail.

The second type of discrete magnetic structures consists of solitary compressions of the lobe field. The compressions have amplitudes from 2 to 6 nT and last 5 to 30 minutes. These events are closely correlated with substorm onsets. They appear to be peripheral encounters with the plasmoids that make up the first class of events.

The third type of transient features are best described by how they differ from plasmoids. Whereas plasmoids cause a bipolar signature in Bz and have a weak field at their center, events of the new class have bipolar signatures in either Bz or By and have strong fields at their center. Whereas the axis of a plasmoid is y-aligned, the axis of the new kind of structures is x-aligned. They have the characteristics of magnetic flux ropes lying parallel to the tail.