terplanetary magnetic field (IMF) By component. And the
polarity of IMF and plasmoid / flux rope By components do
indeed agree. This results indicate that the IMF By pene-
trates plasmoids and the magnetic structures must therefore
be three-dimensional. In this note, the dynamical processes
of magnetotail in the course of a substorm are studied using
a MHD code with two-dimensions and three components on
the basis of two types of initial equilibrium solutions of the
quiet magnetotail. The numerical results of two cases illus-
trate various features of time evolution of By component that
correspond to two kinds of plasmoid-like structures: one is
associated with a flux rope core and the other resembles a
“closed loop” plamoid. Therefore, the occurrence of various
magnetic structures in the magnetotail might be related to
nonsteady driven reconnection with different distributions of
the By component.
A preliminary exploration of
the mechanism for the occur-
rence of two types of various
magnetic structures in the
magnetotail
JIN Shuping1, HU Xianpeng1, CUI Hailong1,
LIU Zhenxing2, PU Zuyin3 & B. Wilken4
1. Department of Earth and Space Science, University of Science and
Technology of China, Hefei 230026, China;
2. Center for Space Sciences and Application Research, Chinese Acad-
emy of Sciences, Beijing 100080, China;
3. Department of Geophysics, Peking University, Beijing 100871, China;
4. Max-Planck Institut fuer Aeronomie, D-37191 Katlanburg-Lindau,
Germany
Keywords: magnetospheric substorm, magnetic cross-tail compo-
nent By, plasmoid-like structures, nonsteady magnetic reconnection.
Observations of magnetic structures in the magneto-
tail have frequently shown bipolar perturbations in the B
component of the magnetic field. These are thought to be
Abstract
As well known, the magnetic cross-tail compo-
nent By in the magnetotail is in direct proportion to the in-
B
z
(Continued from page 980)
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(Received November 30, 2000)
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