TY - JOUR
T1 - Multiscale temporal variations of pulsating auroras
T2 - On-off pulsation and a few Hz modulation
AU - Nishiyama, Takanori
AU - Sakanoi, Takeshi
AU - Miyoshi, Yoshizumi
AU - Hampton, Donald L.
AU - Katoh, Yuto
AU - Kataoka, Ryuho
AU - Okano, Shoichi
PY - 2014/5
Y1 - 2014/5
N2 - 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
AB - 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
KW - energetic electron precipitation
KW - ground-based observations
KW - high-speed imaging
KW - pulsaing aurora
KW - wave-particle interactions
KW - whistler mode chorus
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U2 - 10.1002/2014JA019818
DO - 10.1002/2014JA019818
M3 - Article
AN - SCOPUS:84902477718
SN - 2169-9380
VL - 119
SP - 3514
EP - 3527
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 5
ER -