Detection of geomagnetically aligned currents associated with an auroral arc

Cloutier, P. A.; Anderson, H. R.; Park, R. J.; Vondrak, R. R.; Spiger, R. J.; Sandel, B. R.

doi:10.1029/ja075i013p02595

Cited by 128 publications

(28 citation statements)

References 5 publications

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“…Measurements indicating the existence of highlatitude field-aligned currents have been reported by Park and Cloutier (1971), and both field-aligned particle fluxes and field-aligned currents were detected by Choy et al (1971) and Cloutier et al (1970).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous particle and field observations of field-aligned currents

Berko¹,

Hoffman²,

Burton³

et al. 1975

J. Geophys. Res.

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Simultaneous measurements of low‐energy precipitating electrons and magnetic fluctuations from the low‐altitude polar‐orbiting satellite Ogo 4 have been compared. Analysis of the two sets of experimental data for isolated events led to the classification of high‐latitude field‐aligned currents as purely temporal or purely spatial variations. Magnetic field disturbances calculated by using these simple current models and the measured particle fluxes were in good agreement with measured field values. Although fluxes of electrons of greater than 1 keV were detected primarily on the night side, magnetometer disturbances indicative of field‐aligned currents were seen at all local times, in both the visual auroral regions and the day side polar cusp. Thus electrons with energies of less than ∼1 keV are the prime charge carriers in high‐latitude day side field‐aligned currents. The satellite measurements are in good agreement with previously measured field‐aligned current values and with values predicted from several models involving magnetospheric field‐aligned currents.

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Section: Introductionmentioning

confidence: 99%

Simultaneous particle and field observations of field-aligned currents

Berko¹,

Hoffman²,

Burton³

et al. 1975

J. Geophys. Res.

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“…This difference is probably due to such factors as (a) that the current spreads out at high altitudes so that we are only taking the region of concentrated current as the current layer at high altitudes and (b) that both studies are still exploratory and that the basis of the selections of the cases for demonstration is not the same. Cloutier et al (1970) and Park and Cloutier (1971) studied the currents associated with a quiet auroral arc by a rocket-borne magnetometer experiment. They deduced a pair of oppositely directed field-aligned current sheets, the poleward sheet with an upward current being coincident with the visible arce and the equatorward sheet with a downward current being displaced to the south of the visible arc.…”

Section: 17mentioning

confidence: 99%

Identifications of the polar cap boundary and the auroral belt in the high-altitude magnetosphere: A model for field-aligned currents

Sugiura¹

1975

J. Geophys. Res.

116

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Using the OGO-5 GSFC-fluxgate magnetometer data, the polar cap boundary is identified in the high-altitude magnetosphere by a sudden transition from a dipolar field to' a more tail-like configuration. It is inferred that there exists a field-aligned current layer at the polar cap boundary. In the nightside magnetosphere the polar cap boundary is identified as the high-latitude boundary of the plasma sheet. The fieldaligned current flows downward to the ionosphere on the morning side of the magnetosphere and upward from the ionosphere on the afternoon side.Thus in the high-latitude boundary layer of the plasma sheet in the tail, the current is toward the earth in the post-midnight region and away from the earth before midnight. The basic pattern of the magnetic field variations observed during the satellite's traversal of the auroral belt is presented. This pattern shows the existence of a field-aligned current layer on the equator side of the polar cap boundary. Currents flow in the opposite directions in the two field-aligned current layers. The current directions in these layers as observed by OGO-5 in the highaltitude magnetosphere are the same as those observed at low altitudes by the polar orbiting TRIAD satellite (Armstrong and Zmuda, 1973). The magnetic field in the region where the lower-latitude field-aligned current layer is situated is essentially meridional. Thus the equatorial current closure of this current system must be via the equatorial current sheet. The two field-aligned current systems, one at the polar cap boundary and the other on the low-latitude side of the auroral belt, are coupled through the Pedersen current in the ionosphere. The coupling is weak during magnetically quiet periods and becomes strong at disturbed times.Even during intense disturbances the basic pattern of the field variations in the critical regions of the auroral belt and the polar cap boundary is the same as at quiet times. Intensifications of the field-aligned currents and the appearances of multiple pairs of field-aligned current layers characterize the disturbed conditions of these regions.

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“…Following an early study of BSTROM (1964), the field-aligned currents, feeding the ionospheric electrojet system in the region of the auroras, became a subject of considerable interest by the middle 1970's (CLOUTIER et al, 1970;CHOY et al, 1971;PARK and CLOUTIER, 1971;WHALEN and MCDIARMID, 1972;ANDERSON and CLOUTIER, 1975;ARMSTRONG et al, 1975;CASSERLY and CLOUTIER, 1975;PAZICH and ANDERSON, 1975;SPIGER and ANDERSON, 1975;DAVIS and HALLINAN, 1976;KAMIDE et al, 1976a, b;and MALTSEV et al, 1977).…”

Section: Auroral Electrojet Current and Luminositymentioning

confidence: 99%

Highlights in the studies of the relationship of geomagnetic field changes to auroral luminosity.

Campbell¹

1978

J. geomagn. geoelec

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In the middle of the 18th century Celsius observed that there was a correspondence between a great aurora in Europe and the extreme motion of his observed compass needle. By the nineteenth century it was well established that the geomagnetic field always fluctuated violently at the height of an auroral display, that the high latitude zones of peak field disturbance and luminosity had similar locations, and that there were concurrent solar cycle changes in activity levels for the two phenomena. After the International Geophysical Year of 1957 to 1959 the correspondence of the ionospheric electrojet currents and auroral forms became a focus of observational programs. In these recent times the studies of a relationship between short-period pulsations of the geomagnetic field and luminosity pulsations (or the pulsations of bombarding, low energy electrons causing the auroral intensity changes) appeared prominently in the literature. A summary of the scientific progress in the study of these phenomena is presented in this paper.

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Detection of geomagnetically aligned currents associated with an auroral arc

Cited by 128 publications

References 5 publications

Simultaneous particle and field observations of field-aligned currents

Simultaneous particle and field observations of field-aligned currents

Identifications of the polar cap boundary and the auroral belt in the high-altitude magnetosphere: A model for field-aligned currents

Highlights in the studies of the relationship of geomagnetic field changes to auroral luminosity.

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