Multiscale temporal variations of pulsating auroras: On-off pulsation and a few Hz modulation

Takanori Nishiyama, Takeshi Sakanoi, Yoshizumi Miyoshi, Donald L. Hampton, Yuto Katoh, Ryuho Kataoka, Shouichi Okano

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A statistical study on the cross-scale property on the temporal variations of pulsating aurora intensity was conducted on 53 events observed at the Poker Flat Research Range during the period from 1 December 2011 to 1 March 2012. The observed modulation frequency ranged from 1.5 to 3.3 Hz, and strong modulations were not seen in the frequency range higher than about 3 Hz. This suggests that the time of flight of electrons has a time-smoothing effect on the more rapid variations above 3 Hz. Furthermore, the frequency of modulation showed relatively strong correlation to auroral intensity (correlation coefficient of 0.58), and it can be explained with nonlinear wave growth theory, in which the modulation frequency increases with the wave amplitude of the whistler mode chorus. In contrast, the on-off pulsations showed no significant correlations with auroral intensity. This result probably implies that several different plasma processes with different time scales from nonlinear wave growth should be taken into account when determining the on-off periods. In particular, we suggest that long-term variations in the cold plasma density play a dominant role in controlling the conditions of wave-particle interactions that have temporal scale of the on-off pulsation periods. Key Points A statistical study on the cross-scale property on the temporal variations of PA The on-off periods and modulation frequency ranged 1.6-15 s and 1.5-3.3 Hz The modulation frequency showed strong correlation to aurora intensity

Original languageEnglish
Pages (from-to)3514-3527
Number of pages14
JournalJournal of Geophysical Research: Space Physics
Volume119
Issue number5
DOIs
Publication statusPublished - 2014 May

Keywords

  • energetic electron precipitation
  • ground-based observations
  • high-speed imaging
  • pulsaing aurora
  • wave-particle interactions
  • whistler mode chorus

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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