Open Flux Merging in an Expanding Polar Cap Model

  1. T. E. Moore,
  2. J. H. Waite Jr.,
  3. T. W. Moorehead and
  4. W. B. Hanson
  1. J. J. Moses1 and
  2. G. L. Siscoe2

Published Online: 18 MAR 2013

DOI: 10.1029/GM044p0247

Modeling Magnetospheric Plasma

Modeling Magnetospheric Plasma

How to Cite

Moses, J. J. and Siscoe, G. L. (1988) Open Flux Merging in an Expanding Polar Cap Model, in Modeling Magnetospheric Plasma (eds T. E. Moore, J. H. Waite, T. W. Moorehead and W. B. Hanson), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM044p0247

Author Information

  1. 1

    Space Science Laboratory, The Aerospace Corporation, P.O. Box 92957, Los Angeles, California 90009

  2. 2

    Department of Atmospheric Science, UCLA, Los Angeles, California 90024

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780875900704

Online ISBN: 9781118664414



  • Space plasmas—Mathematical models;
  • Magnetosphere—Mathematical models;
  • Ionosphere—Mathematical models


We present calculated ionospheric convection patterns that result from dayside magnetic merging when open and closed flux tubes are cut. In the model a boundary representing the boundary between open and closed field lines expands as newly open flux enters through a gap on the dayside. The gap which represents the dayside merging region mapped to the ionosphere is extended into the polar cap to represent open field line merging. It has been suggested that it is necessary to extend the ionospheric image of the merging line into the polar cap to account for sunward flows observed there. We show how the length and the merging potential associated with the extended merging line affects the resulting flow patterns. We compare the results to relevant published data and find that an extended merging line indeed induces sunward polar cap flow, but the observed sunward flow is better explained by a day-night ionospheric conductivity gradient.