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Multiple time-scale beats in aurora: precise orchestration via magnetospheric chorus waves.
K Hosokawa1,2, Y Miyoshi3, M Ozaki4
1Graduate School of Informatics and Engineering, University of Electro-Communications, Chofu, Tokyo, Japan. keisuke.hosokawa@uec.ac.jp.
Scientific Reports
|February 27, 2020
Summary
Auroral brightness fluctuations are linked to space plasma waves. Sub-second auroral beats are controlled by chorus wave chirping, revealing wave-particle interactions drive aurora dynamics.
Area of Science:
- Space Physics
- Plasma Physics
- Atmospheric Science
Background:
- Auroral brightness exhibits complex periodic variations, often with multiple coexisting timescales.
- The precise origin of these multi-timescale auroral beats has remained unclear due to limitations in observational temporal resolution.
Purpose of the Study:
- To investigate the underlying physical mechanisms responsible for the multi-timescale beats observed in auroral displays.
- To establish a direct correlation between auroral dynamics and electromagnetic wave phenomena in Earth's magnetosphere.
Main Methods:
- Coordinated observations using ultrafast auroral imagers in the Arctic.
- Simultaneous measurements from the Arase (Advanced Reference Concept for Space Exploration) magnetospheric satellite.
- Analysis of auroral beat periods and electromagnetic wave intensity modulations, specifically chorus waves.
Main Results:
- A strong agreement was found between the beat periods of aurorae and the intensity modulations of chorus waves.
- Sub-second auroral scintillations were precisely correlated with fine-scale chirping rhythms in chorus waves.
- This correlation provides direct evidence linking magnetospheric wave activity to auroral displays.
Conclusions:
- The resonant interaction between energetic electrons and chorus waves in the magnetosphere is the primary driver of complex auroral behaviors.
- This finding elucidates the physical processes governing auroral dynamics on Earth and potentially on other magnetized planets.
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