Northward IMF and patterns of high-latitude precipitation and field-aligned currents: The February 1986 storm

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA06p07893· OSTI ID:5311138

Rich, F J; Hardy, D A; Redus, R H; Gussenhoven, M S ^[1]

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1. Air Force Geophysics Laboratory, Hanscom AFB, MA (USA)

On February 7, 1986, during a major geomagnetic storm the B{sub z} component of the interplanetary magnetic field (IMF) turned strongly northward for several hours. Following the northward turning, the equatorward boundary of the auroral zone on the nightside contracted sharply poleward and polar cap arcs were observed. The strength of the region 1 / region 2 currents decreased markedly and became immeasurably small at the time of the maximum contraction of the auroral oval. An NBZ current system was observed to grow and expand in the southern (summer) high latitude region over a period of more than 2 hours. Simultaneously, an irregular pattern of field-aligned currents was observed in the northern (winter) hemisphere. During the contraction, the latitudinal width of the auroral region mapping to the central plasma sheet (CPS) decreased dramatically while the width of the area mapping to the boundary plasma regions (BPR) in the magnetosphere increased greatly. At the time of the maximum contraction the BPR extended up to a latitude of at least 87.1{degree}. The NBZ currents expanded with and were entirely located within the BPR precipitation. Polar cap arcs were observed in both regions of BPR precipitation and polar cap precipitation and were not correlated with the location of the large-scale field-aligned currents. There was no indication of the CPS intruding to high latitudes, and thus no evidence for bifurcation of the magnetotail. The boundary between the CPS and BPR showed little change. If this implies that the boundary between open and closed field lines contracted slowly or not at all, then a significant portion of the observed BPR precipitation was observed along open field lines.

• OSTI ID: 5311138
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:A6; 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
AURORAL ZONES
CHARGED-PARTICLE PRECIPITATION
CORRELATIONS
CURRENTS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
EXPANSION
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FIELDS
MAGNETIC STORMS
MAGNETOTAIL
ORIENTATION
PLASMA SHEET
POLAR REGIONS
SATELLITES