Small-scale dynamic auroras have spatial scales of a few km or less, and temporal scales of a few seconds or less, which visualize the complex interplay among charged particles, Alfvén waves, and plasma instabilities working in the magnetosphere-ionosphere coupled regions. We summarize the observed properties of flickering auroras, vortex motions, and filamentary structures. We also summarize the development of fundamental theories, such as dispersive Alfvén waves (DAWs), plasma instabilities in the auroral acceleration region, ionospheric feedback instabilities (IFI), and the ionospheric Alfvén resonator (IAR).
Supplementary Information: The online version contains supplementary material available at 10.1007/s11214-021-00796-w.
Bibliographical noteFunding Information:
The work of RK was supported by JSPS Kakenhi (25302006, 15H02628, 16H06286). C.C. Chaston was supported by ISSI and through NASA grant NNX17AI55G. T.-H. Watanabe was supported by ISSI and by JSPS KAKENHI Grant Number JP16H04086 and JP17H01177. D.K. Whiter was supported by ISSI and NERC (UK) through grant NE/S015167/1. Movies 4, 6 and 7 are from the ASK instrument which has been funded by PPARC, STFC (PP/C502614/1) and NERC (NE/H024433/1, NE/N004051/1) of the United Kingdom and Vetenskapsrådet of Sweden. The authors wish to thank the International Space Science Institute ISSI-Bern for organization of this review and for financial support of the team meeting.
© 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature.
- Auroral breakup
- Auroral phenomena
- Dispersive Alfven waves
- Flickering aurora
- Ionospheric Alfven resonator
- Ionospheric feedback instabilities
- Magnetosphere-ionosphere coupled region