Multiple-satellite studies of magnetospheric substorms: plasma sheet recovery and the poleward leap of auroral zone activity

Journal Article · Wed Nov 01 04:00:00 EST 1978 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA083iA11p05256· OSTI ID:6588248

Pytte, T; McPherron, R L; Kivelson, M G; West, Jr, H I; Hones, Jr, E W

Particle observations from pairs of satellites (Ogo 5 and Vela 4A and 5A) during 28 plasma sheet thickening events are examined. These data indicate that thickening of the nighttime plasma sheet during substorms occurs in two main stages, one early stage of single or multiple expansions of the near-earth (geocentric distances r< or approx. =15R/sub E/) plasma sheet at the onset of substorm expansions (Pi 2 bursts) on the ground and another later stage of plasma sheet recovery that starts near the time of maximum auroral zone bay activity and is characterized by a large-scale thickening toward higher latitudes that occurs over a broad azimuthal scale and from ionospheric heights to beyond the Vela orbit (rapprox.18R/sub E/). A detailed analysis of two-satellite observations during eight plasma sheet recoveries is presented, showing events that occurred within 5 min in widely separated locations at small (<4R/sub E/) distances from the tail's midplane and events that occurred concurrently in the Vela orbit and at high latitudes in the near-earth region. Some events were accompanied by clear signatures of a poleward leap (to >71/sup 0/ magnetic latitude) of electron precipitation and the westward electrojet that probably corresponded to an expansion poleward of the ionospheric projection of the recovering plasma sheet. The eight plasma sheet recoveries occurred 10--30 min after a Pi 2 burst on the ground, and mid-latitude magnetograms showed no indications of a near-coincident formation of a substorm current wedge in the local time sector of the spacecraft; this indicates that the plasma sheet recoveries and the poleward leaps were not caused directly by a late high-latitude substorm expansion. Instead, these phenomena seem to represent a transition phase between a substorm expansion sequence and a substorm recovery.

• Research Organization: Department of Physics, University of Bergen, N-5014 Bergen, Norway
• OSTI ID: 6588248
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 83:A11; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
CHARGED-PARTICLE PRECIPITATION
CURRENTS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ELECTROJETS
ELECTRON PRECIPITATION
EXPANSION
MAGNETIC BAYS
MAGNETOSPHERE
OGO SATELLITES
PLASMA EXPANSION
PLASMA SHEET
SATELLITES