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Geotail observations of magnetospheric midtail during an extended period of strongly northward interplanetary magnetic field
Author(s) -
Huang ChaoSong,
Foster J. C.,
Song P.,
Sofko G. J.,
Frank L. A.,
Paterson W. R.
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl014170
Subject(s) - magnetosphere , physics , interplanetary magnetic field , geophysics , earth's magnetic field , solar wind , interplanetary spaceflight , plasma , ionosphere , substorm , geomagnetic storm , astrophysics , magnetic field , quantum mechanics
A number of simulations have predicted a closed magnetosphere after several hours of northward interplanetary magnetic field (IMF). During January 7–8, 1998, the IMF was strongly northward for ∼21 hours without any southward excursion. The Geotail spacecraft was located at −21 > X gsm > −28 R E and very close to the magnetospheric equatorial plane and midnight, and detected two distinct regions. In the inner region close to the equatorial plane, the geomagnetic field is weak, the plasma pressure and plasma beta are high, and plasma flow is sunward. The outer region is characterized by lower plasma pressure and antisunward plasma flow. The observations are consistent with a closed magnetosphere and may represent the ground state of the magnetosphere.