The interplanetary magnetic field B sub y -dependent field-aligned current in the dayside polar cap under quiet conditions

Journal Article · Wed Mar 01 04:00:00 EST 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA03p02684· OSTI ID:5839089

Yamauchi, M ^[1]; Araki, T ^[2]

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1. Univ. of Alaska, Fairbanks (USA) Kyoto Univ. (Japan)
2. Kyoto Univ. (Japan)

Spatial distribution and temporal variation of the interplanetary magnetic field (IMF) B{sub y}-dependent cusp region field-aligned currents (FACs) during quiet periods were studied by use of magnetic data observed by Magsat. The analysis was made for 11 events (each event lasts more than one and a half days) when the IMF B{sub y} component was steadily large and B{sub x} was relatively small ({vert bar}B{sub z}{vert bar} < {vert bar}B{sub y}{vert bar}). Results of the analysis of total 62 half-day periods for the IMF B{sub y}-dependent cusp region FAC are summarized as follows: (1) the IMF B{sub y}-dependent cusp region FAC is located at around 86{degree}-87{degree} invariant latitude local noon, which is more poleward than the location of the IMF B{sub z}-dependent cusp region FAC; (2) the current density of this FAC is greater than previous studies ({ge} 4 {mu}A/m{sup 2} for IMF B{sub y} = 6 nT); (3) there are two time scales for the IMF B{sub y}-dependent cusp region FAC to appear: the initial rise of the current is on a short time scale, {approximately} 10 min, and it is followed by a gradual increase on a time scale of several hours to a half day; (4) the seasonal change of this FAC is greater than that of the nightside region 1 or region 2 FACs; (5) the IMF B{sub z}-dependent cusp region FAC is not well observed around the cusp when the IMF B{sub y}-dependent cusp region FAC is intense.

• OSTI ID: 5839089
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A3; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
&amp; Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
CURRENT DENSITY
CURRENTS
DATA ANALYSIS
DISTRIBUTION
ELECTRIC CURRENTS
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FIELDS
MAGNETOMETERS
MEASURING INSTRUMENTS
POLAR CUSP
POLAR REGIONS
SEASONAL VARIATIONS
SPATIAL DISTRIBUTION
VARIATIONS