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Lessons from the ring current injection during the September 24, 25, 1998 storm
Author(s) -
Russell C. T.,
Lu Gang,
Luhmann J. G.
Publication year - 2000
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 - 10.1029/1999gl003718
Subject(s) - ring current , solar wind , geomagnetic storm , magnetosphere , interplanetary spaceflight , physics , geophysics , earth's magnetic field , current (fluid) , flux (metallurgy) , atmospheric sciences , storm , environmental science , poynting vector , dissipation , meteorology , magnetic field , plasma , materials science , nuclear physics , quantum mechanics , metallurgy , thermodynamics
Because the conditions in the solar wind that lead to the injection of energetic particles into the ring current simultaneously affect a variety of geomagnetic phenomena, it is often difficult to determine whether these magnetospheric processes are causally related or are simply contemporaneous. The sequence of interplanetary conditions leading up to the September 24–25, 1998 geomagnetic storm are particularly suited to illustrating what conditions lead to significant activity in the auroral zone as distinct from the injection into the ring current. This interval illustrates that the magnetosphere requires a period of strong, steady, not time‐varying, convection for the buildup of the ring current, and that the AE index cannot be used to forecast the ring current buildup. Furthermore, when the ring current reached its peak strength, it contained 6 PJ and was dissipating energy at a rate of about 0.4 TW. The northern auroral regions and southern added another 1.2 TW of dissipation. This rate of dissipation could be maintained readily by the mechanical energy flux of the solar wind of about 40 TW but would require coupling to much of the incident solar‐wind Poynting flux if that were the sole energy source.