Giacobini-Zinner Magnetotail: Ice Magnetic Field Observations

  1. Thomas J. Birmingham and
  2. Alexander J. Dessler
  1. J.A. Slavin1,
  2. E.J. Smith1,
  3. B.T. Tsurutani1,
  4. G.L. Siscoe2,
  5. D.E. Jones3 and
  6. D.A. Mendis4

Published Online: 19 MAR 2013

DOI: 10.1029/SP027p0266

Comet Encounters

Comet Encounters

How to Cite

Slavin, J.A., Smith, E.J., Tsurutani, B.T., Siscoe, G.L., Jones, D.E. and Mendis, D.A. (1988) Giacobini-Zinner Magnetotail: Ice Magnetic Field Observations, in Comet Encounters (eds T. J. Birmingham and A. J. Dessler), American Geophysical Union, Washington, D.C.. doi: 10.1029/SP027p0266

Author Information

  1. 1

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

  2. 2

    Department of Atmospheric Sciences, University of California, Los Angeles, CA 90024

  3. 3

    Department of Physics, Brigham Young University, Provo, UT 94601

  4. 4

    Department of Electrical Engineering and Computer Science, University of California, La Jolla 92093

Publication History

  1. Published Online: 19 MAR 2013
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780875902395

Online ISBN: 9781118668757



  • Cometocentric solar ecliptic (CSE);
  • Giacobini-Zinner magnetotail;
  • International Cometary Explorer (ICE);
  • Interplanetary magnetic field (IMF);
  • Magnetotail dimensions;
  • Tail boundary current layer


The ICE magnetic field observations at Comet Giacobini-Zinner have revealed the presence of a well developed magnetotail with a diameter of ∼10,000 km at a distance of 7,800 km downstream of the nucleus. The tail is composed of two lobes of opposite magnetic polarity separated by a ∼1,500 km thick plasma sheet. A ∼250 km diameter region of twisted, high intensity magnetic fields was observed in the plasma sheet and may correspond to a cometary “flux rope.” The magnetotail is bounded by a thin, ∼200 km wide magnetopause-like current layer. The field magnitude increases by a factor of 2 between the outer portions of the lobe and the central regions where peak fields of ∼60 nT were measured. The magnetic field in the lobes of the near-tail region is highly flared with the field making a mean angle of about 20° with the symmetry axis. Flaring is observed to be least in the high field regions of the central tail and greatest in the outer portions of the lobes where minimum variance analyses on the magnetopause crossings provided flare angles of 20–400 °. The cross-tail current layer is quite broad and occupies the full width of the plasma sheet. Minimum variance analysis indicates that it was inclined to the plane of the ecliptic by 43°. This current sheet orientation is consistent with the observed direction of the IMF in the Y-Z plane during the ICE fly-by. It is concluded on the basis of these results that the ICE magnetic field observations downstream of Giacobini-Zinner have confirmed the Alfven field line draping model of type I cometary tails.