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Estimates of current changes in the geomagnetotail associated with a substorm
Author(s) -
Lui A. T. Y.
Publication year - 1978
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/gl005i010p00853
Subject(s) - substorm , plasma sheet , current (fluid) , geophysics , ionosphere , current sheet , magnetic field , current density , plasma , physics , field (mathematics) , magnetosphere , magnetohydrodynamics , nuclear physics , mathematics , quantum mechanics , pure mathematics , thermodynamics
Magnetic field variations in the near‐earth magnetotail during a weak magnetospheric substorm are studied by two approximate methods to estimate quantitatively the changes in the cross‐tail current. Analysis of the event indicates that the magnetic field variations can be interpreted as a tailward retreat of the cross‐tail current sheet location by ∼0.4‐3.5 R E and an overall reduction of the current density by ∼5‐25%. These changes are accompanied by enhancement of magnetic field‐aligned currents and earthward flowing plasma. The general features of the observations are consistent with the idea that the cross‐tail currents is being diverted into the ionosphere at the substorm onset in association with earthward drainage of plasma in the plasma sheet.