Average plasma and magnetic field variations in the distant magnetotail associated with near‐Earth substorm effects

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Abstract
Examination of many individual event periods in the ISEE 3 deep tail data set collected in 1982–1983 has suggested that magnetospheric substorms produce a characteristic pattern of effects in the distant magnetotail. ISEE 3 data are appropriate for the study of these effects, since the spacecraft remained relatively fixed within the nominal tail location for long periods. Using auroral electrojet indices (AE and AL) and geostationary orbit particle data to time substorm onsets at earth, we have performed superposed epoch analyses of ISEE 3 and near‐earth data prior to and following substorm expansive phase onsets. Individual events illustrate the wide range of variations possible throughout the magnetosphere, while epoch‐averaged results illustrate the general properties of the deep tail pattern of response to global substorm‐induced dynamical effects. During the growth, or tail energy storage, phase of substorms the distant magnetotail appears to grow diametrically in size, often by many earth radii. Subsequently, about 20–40 min after the substorm expansive phase onset at earth the distant tail undergoes a repeatable sequence of plasma, field, and energetic particle variations as large‐scale plasmoids move rapidly down the tail following their disconnection from the near‐earth plasma sheet.