The plasma wave environment of an auroral arc: 2. Ulf waves on an auroral arc boundary

Gelpi, C.; Bering, Edgar A.

doi:10.1029/ja089ia12p10847

Cited by 23 publications

(13 citation statements)

References 31 publications

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“…The lower energy part is probably due to a localised acceleration of ionospheric electrons by the Alfvén wave electric field. Similar observations of dispersive electron fluxes which often are located near auroral arc boundaries, have been presented by Mc Fadden et al (1986), Gelpi and Bering (1984) and Ivchenko et al (1999).…”

Section: Overview Of Observationssupporting

confidence: 62%

Astrid-2 and ground-based observations of the auroral bulge in the middle of the nightside convection throat

et al. 2001

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Abstract.Results concerning the electrodynamics of the nightside auroral bulge are presented based on simultanous satellite and ground-based observations. The satellite data include Astrid-2 measurements of electric fields, currents and particles from a midnight auroral oval crossing and Polar UVI images of the large-scale auroral distribution. The ground-based observations include STARE and SuperDARN electric fields and magnetic records from the Greenland and MIRACLE magnetometer network, the latter including stations from northern Scandinavia north to Svalbard. At the time of the Astrid-2 crossing the ground-based data reveal intense electrojet activity, both to the east and west of the Astrid-2 trajectory, related to the Polar observations of the auroral bulge but not necessarily to a typical substorm. The energetic electron fluxes measured by Astrid-2 across the auroral oval were generally weak being consistent with a gap observed in the auroral luminosity distribution. The electric field across the oval was directed westward, intensifying close to the poleward boundary followed by a decrease in the polar cap. The combined observations suggests that Astrid-2 was moving close to the separatrix between the dusk and dawn convection cells in a region of low conductivity. The constant westward direction of the electric field across the oval indicates that current continuity was maintained, not by polarisation electric fields (as in a Cowling channel), but solely by localized up-and downward field-aligned currents in good agreement with the Astrid-2 magnetometer data. The absence of a polarisation electric field and thus of an intense westward closure current between the dawn and dusk convection cells is consistent with the relatively weak precipitation and low conductivity in the convection throat. Thus, the Cowling current model is not adequate for describing the electrodynamics of the nightside auroral bulge treated here.

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Section: Overview Of Observationssupporting

confidence: 62%

Astrid-2 and ground-based observations of the auroral bulge in the middle of the nightside convection throat

et al. 2001

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“…Quasiperiodic structures in the ULF-frequency range are frequently observed in the auroral region. Sounding rocket [Gelpi and Bering, 1984;Marklurid et al, 1981;Boehm et el., 1990] and satellite [Knudsen et el., 1990] observations of wave-like disturbances have been reported. As single point observations are problematic for distinguishing between temporal and spatial variations, the oscillating behaviour was interpreted in terms of either low frequency waves or structured field aligned currents.…”

Section: Introductionmentioning

confidence: 99%

Quasiperiodic oscillations observed at the edge of an auroral arc by auroral turbulence 2

Ivchenko

Marklund

Lynch

et al. 1999

Geophysical Research Letters

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“…These shears can, in turn, seed waves at higher frequencies (ion cyclotron to lower hybrid) which can energize ions. In the ionosphere, evidence of such wave steepening is abundant [Pfaff et al, 1987;Tsunoda, 1988;Yamamoto et al, 1994], and detection of plasma waves near the edges of auroral arcs is very common [e.g., Bering et al, 1975;Kelley and Carlson, 1977;Bering, 1984;Gelpi and Bering, 1984].…”

Section: In Situ Observationsmentioning

confidence: 99%

Inhomogeneous plasma flows: A review of in situ observations and laboratory experiments

Amatucci¹

1999

J. Geophys. Res.

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Abstract. Sheared flows in near-Earth space plasmas, both magnetic-field-aligned and cross-field, contribute to a rich array of phenomena which can be simulated in the laboratory. This has led to improved knowledge of the basic processes involving velocity shear operative in space, where it is not possible to conduct detailed and repeatable experiments with control over background parameters. Depending upon the flow characteristics, shear can contribute to either growth or damping of various plasma modes or, if sufficiently strong, can itself drive instabilities. These instabilities can have significant consequences in redefining the plasma equilibrium and can lead to energization and transport. A number of laboratory experiments have been performed to investigate the detailed physics associated with inhomogeneous space plasma flows. In this work, a review of in situ observations of processes associated with sheared flows and details of complementary laboratory experimental investigations is presented.

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The plasma wave environment of an auroral arc: 2. Ulf waves on an auroral arc boundary

Cited by 23 publications

References 31 publications

Astrid-2 and ground-based observations of the auroral bulge in the middle of the nightside convection throat

Astrid-2 and ground-based observations of the auroral bulge in the middle of the nightside convection throat

Quasiperiodic oscillations observed at the edge of an auroral arc by auroral turbulence 2

Inhomogeneous plasma flows: A review of in situ observations and laboratory experiments

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