Fine-scale dynamics of black auroras obtained from simultaneous imaging and particle observations with the Reimei satellite

Y. Obuchi, T. Sakanoi, K. Asamura, A. Yamazaki, Y. Kasaba, M. Hirahara, Y. Ebihara, S. Okano

研究成果: Article査読

8 被引用数 (Scopus)

抄録

To clarify the characteristics and generation process of black auroras, we investigated 13 black auroral events using simultaneous imaging and particle data from the Reimei satellite obtained between November 2005 and October 2006. The formation and motion of black auroras were determined from successive monochromatic auroral images around the satellite's magnetic footprints, while the auroral intensities at the footprints were compared with precipitating electrons. 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 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. Drifting black patches were also observed. We estimated the speed and direction of the drift by minimum mean squared error analysis.

本文言語English
論文番号A00K07
ジャーナルJournal of Geophysical Research: Space Physics
116
7
DOI
出版ステータスPublished - 2011

ASJC Scopus subject areas

  • Space and Planetary Science
  • Geophysics

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