Simultaneous Observation of the Poleward Expansion of Substorm Electrojet Activity and the Tailward Expansion of Current Sheet Disruption in the Near-Earth Magnetotail

RE LOPEZ*, HEJ KOSKINEN, T.I. Pulkkinen, T BOSINGER, RW MCENTIRE, TA POTEMRA

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

In this paper we present observations of a substorm that occurred on June 7, 1985. The data consist of energetic ion and magnetic field data from AMPTE/CCE, magnetometer data from the ground stations of the EISCAT magnetometer cross, STARE radar data, and Pi 1 data from Sodankyla. CCE was in the Finnish local time sector, and the model field line threading CCE came down near the center of the EISCAT magnetometer cross. Furthermore, CCE was located near the neutral sheet and observed the disruption of the cross-tail current in situ. At 2209 UT, Sodankyla registered a Pi 1 burst and the EISCAT stations recorded the onset of a negative bay. Simultaneously, CCE observed the onset of current sheet disruption and ion energization. The energetic ions observed during this initial burst had gyrocenters earthward of CCE. An intensification of activity occurred at 2212 UT, and it was observed essentially simultaneously on the ground and in space. It consisted of an intensification of Pi 1 activity, an intensification of the westward electrojet poleward of the initial breakup latitude (as determined from magnetometer and radar data), and magnetic turbulence and a burst of energetic ions at CCE in the magnetotail. Significantly, this second burst was composed only of ions with gyrocenters tailward of the satellite, and the magnetic turbulence was considerably weaker than that observed during the initial current disruption. This strongly suggests that the current disruption region had moved tailward of CCE. The event provides a direct observational link between the tailward expansion of active regions in the near-Earth magnetotail and the poleward expansion of ionospheric electrojet activity during substorms.

Original languageEnglish
Pages (from-to)9285-9295
Number of pages11
JournalJournal of Geophysical Research
Volume98
Issue numberA6
DOIs
Publication statusPublished - 1 Jun 1993
MoE publication typeA1 Journal article-refereed

Keywords

  • TWO-DIMENSIONAL OBSERVATIONS
  • WESTWARD TRAVELING SURGE
  • AURORAL-ZONE CURRENTS
  • MAGNETIC-FIELD
  • MAGNETOSPHERIC SUBSTORMS
  • SYNCHRONOUS ORBIT
  • CURRENT WEDGE
  • PLASMA SHEET
  • NEUTRAL SHEET
  • GROWTH-PHASE

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