Fine-Scale Characteristics of Black Aurora and its Generation Process

T. Sakanoi, Y. Obuchi, Y. Ebihara, Y. Miyoshi, K. Asamura, A. Yamazaki, Y. Kasaba, M. Hirahara, T. Nishiyama, Shouichi Okano

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Citation (Scopus)

Abstract

Black aurora is a small-scale (typically a few to 10 km) black structure seen in diffuse aurora, and its generation process has been studied with immense interest. We report the precise characteristics of black aurora based on simultaneous image and particle measurement data and possible generation process. Thirteen black auroral events are identified from the Reimei satellite data, and the relationship between particle and auroral images around the satellite's magnetic footprints is investigated in detail. We found that a number of small-scale deficiencies were embedded in precipitating electrons from the central plasma sheet with energies greater than 2-7 keV and that each deficiency corresponded exactly to black arcs and black patches at the magnetic footprint. Therefore, black arcs and black patches are not associated with a field-aligned potential (such as a divergent potential structure) but probably originate from the suppression of pitch angle scattering. In the black auroral region, low-energy (2-5 keV) inverted-V-type downward electrons (spanning channels that are several tens of kilometers wide) often appear to overlap with high-energy (several keV) plasma sheet electrons.

Original languageEnglish
Title of host publicationAuroral Phenomenology and Magnetospheric Processes
Subtitle of host publicationEarth and Other Planets
PublisherWiley-Blackwell
Pages271-278
Number of pages8
ISBN (Electronic)9781118670286
ISBN (Print)9780875904870
DOIs
Publication statusPublished - 2013 Mar 29

Keywords

  • Acceleration
  • Black aurora
  • Fine scale
  • Image
  • Particle
  • Reimei

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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