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Recurrent embedded substorms during the 19 October 1998 GEM storm
Author(s) -
Henderson M. G.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2015ja022014
Subject(s) - interplanetary magnetic field , storm , geophysics , substorm , interplanetary spaceflight , geology , atmospheric sciences , magnetosphere , physics , plasma , solar wind , meteorology , quantum mechanics
The 18–19 October 1998 GEM (Geospace Environment Modeling) storm was associated with a long interval of remarkably steady southward interplanetary magnetic field. In this study we demonstrate that classical substorms occurred throughout the interval and that the storm appears to be composed of the typical two‐mode response consisting of a recurrent loading/unloading cycle on a timescale of approximately 2–4 h together with an episodic/bursty continuously driven component operating on a timescale of 5–15 min. The loading/unloading activity is manifested as typical poleward expanding “embedded” substorms (embedded into the auroral oval) emerging from the equatorward regions of the auroral distribution, while the continuously driven component is manifested by the episodic ejection of streamers equatorward from poleward boundary activations. The streamers subsequently produce torches and eastward drifting omega bands which likely moderate the need for substorms to occur more frequently than observed.