Multipoint observations of a small substorm

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA11p18897· OSTI ID:5132797

Lopez, R E ^[1]; Luehr, H ^[2]; Anderson, B J; Newell, P T; McEntire, R W ^[3]

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1. Johns Hopkins Univ. Applied Physics Lab., Laurel, MD (United States) Applied Research Corp., Landover, MD (United States)
2. Technische Univ. Braunschweig (West Germany)
3. Johns Hopkins Univ. Applied Physics Lab., Laurel, MD (United States)

In this paper the authors present multipoint observations of a small substorm which occurred just after 0110 UT on April 25, 1985. The observations were made by spacecraft (AMPTE CCE, AMPTE IRM, DMSP F6, and DMSP F7), ground auroral stations (EISCAT magnetometer cross, Syowa, Narssarssuaq, Great Whale River, and Fort Churchill), and mid-latitude stations (Furstenfeldbruck, Toledo, and Argentine Island). These data provide them with a broad range of observations, including the latitudinal extent of the polar cap, visual identification of substorm aurorae and the magnetic perturbations produced directly beneath them, in situ magnetic field and energetic particle observations of the disruption of the cross-tail current sheet, and observations concerning the spatial expansion of the current disruption region from two radially aligned spacecraft. The DMSP data indicate that the event took place during a period when the polar cap was relatively contracted, yet the disruption of the current sheet was observed by CCE at 8.56 R{sub E}. They have been able to infer a considerable amount of detail concerning the structure and westward expansion of the auroral features associated with the event, and they show that those auroral surges were located more than 10{degree} equatorward of the boundary between open and closed field lines. Moreover, they present evidence that the current sheet disruption observed by CCE in the neutral sheet was located on field lines which mapped to the westward traveling surge observed directly overhead of the ground station at Syowa. Furthermore, the observations strongly imply that disruption of the cross-tail current began in the near-Earth region and that it had a component of expansion which was radially antisunward.

• OSTI ID: 5132797
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:A11; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
CHARGED PARTICLES
CURRENTS
DYNAMICS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
EXPANSION
MAGNETIC BAYS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MAGNETOTAIL
MECHANICS
MONITORING
PLASMA SHEET
POLAR-CAP AURORAE
SATELLITES