Seasonal and diurnal variations of the latitude of the westward auroral electrojet in the nightside polar cap

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JA02379· OSTI ID:5257861

Wu, Q; Rosenberg, T J ^[1]; Lanzerotti, L J; Maclennan, C G ^[2]; Wolfe, A ^[3]

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1. Univ. of Maryland, College Park (USA)
2. AT and T Bell Labs., Murray Hill, NJ (USA)
3. City Univ. of New York, Brooklyn (USA)

Simultaneous measurements of magnetic field variations at the nominally conjugate sites of South Pole station, Antarctica, and Iqaluit, Canada, have been used to study latitude differences in the location of corresponding westward electrojets in the nightside polar cap. Substorm-related auroral events were selected from 1986 data with the criterion that the magnitude of the negative bay exceed 100 nT in at least one hemisphere and that the electrojet, oriented mainly in the magnetic east-west direction, pass overhead of this station. The resulting data base comprised 60 events distributed seasonally. The interhemispheric latitude difference in the locations of the electrojets was obtained by examining the ratio of the vertical and horizontal component magnetic variations. Seasonal and diurnal variations of the latitude of westward electrojets were evident during solstice periods. In particular, it is noted that the substorm westward electrojet flows at higher latitudes in the winter hemisphere than in the summer hemisphere, after 2,000 MLT. The latitude difference between the two hemispheres maximizes at {approximately}4{degree} near local midnight. The latitude difference becomes smaller away from midnight and reverses for local times prior to {approximately} 2,000 MLT. The observed seasonal and diurnal variations are generally consistent with predictions of the effect of the magnetic dipole tilt on the location of last closed field lines.

• OSTI ID: 5257861
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A2; 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
COORDINATES
CURRENTS
DAILY VARIATIONS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTROJETS
GEOGRAPHICAL VARIATIONS
LATITUDE EFFECT
MAGNETIC FIELDS
MAGNETOTAIL
PLASMA SHEET
POLAR REGIONS
SEASONAL VARIATIONS
VARIATIONS