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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
A10219,
doi:10.1029/2005JA011541,
2006
Magnetospheric convection during prolonged intervals with southward interplanetary magnetic field
Raymond J. Walker
Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA Department of Earth and Space Sciences, University of California, Los Angeles, California, USA
Maha Ashour-Abdalla
Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA Department of Physics and Astronomy, University of California, Los Angeles, California, USA
Mostafa El Alaoui
Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA
Ferdinand V. Coroniti
Department of Physics and Astronomy, University of California, Los Angeles, California, USA
Abstract
We have used a global magnetohydrodynamic simulation to investigate magnetospheric convection during a prolonged interval
with modest southward driving. The interval simulated occurred on 13 and 14 February 2001 during a period when the interplanetary
magnetic field (IMF) remained weakly southward for over 12 hours. Early in the simulation a near-Earth neutral line located
between 20 R
E
and 40 R
E
in the tail drove flows earthward and then around the near-Earth obstacle to return magnetic flux to the dayside. The earthward
flow led to increased ionospheric conductance and developed a modest earthward pressure gradient in the inner plasma sheet.
Ionospheric line tying slowed the earthward flow. The pressure gradient caused the inner tail to become interchange unstable
and lead to the tailward flow. When the tailward moving flux tube reached the near-Earth neutral line additional reconnection
occurred between the tailward moving flux tube and IMF field lines created by lobe reconnection thereby returning flux to
the nightside tail lobes. Late in the event the new lobe field lines reconnected at the duskside magnetopause creating additional
rapid tailward motion. The tailward flow led to a reduction in both the ionospheric conductance and near-Earth tail pressure
gradient and earthward flow was again established. This sequence repeated at least three times during the interval simulated.
Received 19
November
2005;
accepted 11
August
2006;
published 19
October
2006.
Keywords: magnetospheric convection;
substorms.
Index Terms: 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions (2431); 2790 Magnetospheric Physics: Substorms; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2723 Magnetospheric Physics: Magnetic reconnection (7526, 7835).
Read Full Article (file size: 17157722 bytes) Cited by
Citation: Walker, R. J., M. Ashour-Abdalla, M. El Alaoui, and F. V. Coroniti
(2006),
Magnetospheric convection during prolonged intervals with southward interplanetary magnetic field,
J. Geophys. Res.,
111,
A10219,
doi:10.1029/2005JA011541.
Copyright 2006 by the American Geophysical Union.
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