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Magnetic energy storage and the nightside magnetosphere‐ionosphere coupling
Author(s) -
Horton W.,
Pekker M.,
Doxas I.
Publication year - 1998
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 - 10.1029/1998gl900043
Subject(s) - substorm , magnetosphere , physics , ionosphere , solar wind , geophysics , magnetic cloud , dusk , coupling (piping) , magnetic field , computational physics , interplanetary magnetic field , astronomy , mechanical engineering , quantum mechanics , engineering
The change in the magnetic energy stored in the Earth's magnetotail for the January 14–15 1988 magnetic cloud event is investigated using an empirical magnetic field model. The results are used to calculate the two normal modes contained in the low‐dimensional global model called WINDMI for the solar wind driven magnetosphere‐ionosphere system. For that event, we find that the storage of magnetic energy in the geotail increases most rapidly (by 17%) in the phase where the IMF turns from northward to the dawn‐dusk direction and then by an additional 5% in the phase where the IMF rotates from dawn‐dusk to southward. The coupling of the magnetosphere‐ionosphere (MI) through the night side region 1 current loop transfers power to the ionosphere through two modes: a fast (period of minutes) oscillation and a slow (period of one hour) geotail cavity mode. The solar wind drives both modes in the substorm dynamics.