Field-aligned currents associated with substorms in the vicinity of synchronous orbit. 2. GOES 2 and GOES 3 observations

Journal Article · Sun Mar 01 04:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA03p02432· OSTI ID:5399108

Nagai, T ^[1]

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1. Meteorological Research Inst., Ibaraki (Japan)

Substorm-associated field-aligned currents have been studied using magnetic field observations at synchronous orbit and on the ground. The GOES 2 and GOES 3 satellite pair, separated in local time by about 2 hours, clearly demonstrates local time dependence of field-aligned current signatures at synchronous orbit. The author has made comparisons between magnetic disturbances at synchronous orbit and ground mid-latitude magnetic disturbances. In the morning region and the evening region, D perturbations at two locations have the same sign, indicating that major field-aligned currents are those flowing into (out of) the ionosphere located on L shells greater than the spacecraft L shell in the morning (evening) region. However, the D perturbations at synchronous orbit are more transient than those on the ground in the same local time meridian. Near midnight an opposite sense for the sign of D between synchronous orbit and the ground is frequently observed. In such a case the D perturbation is always negative at synchronous orbit, while the ground D perturbation is positive. The author proposes that the downward current sheet extending from the morningside overlaps the upward current sheet extending from the eveningside in the center of the current system. In this model the double field-aligned current sheets are formed in association with the onset of a substorm expansion phase near the midnight meridian, and the meridian for the major field-aligned currents flowing into the ionosphere shifts progressively eastward in the morning region and the meridian for the major field-aligned currents flowing out of the ionosphere shifts progressively westward in the evening region as substorms progress.

• OSTI ID: 5399108
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A3; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
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CURRENTS
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EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
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MAGNETIC BAYS
MAGNETIC FIELDS
MATHEMATICAL MODELS
MORPHOLOGY
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PLANETARY IONOSPHERES
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TIME DEPENDENCE