The Potential Role of Modified Electron Acoustic Wave and Nonlinear Mode Coupling in Mono‐Energetic Aurora

• Published in: Geophysical research letters 2023-05, Vol.50 (9), p.n/a
• Main Authors: Shi, Run, Liang, Jun, Hu, Zejun, Han, Desheng, Li, Xuejing
• Format: Article
• Language: English
• Subjects: Acceleration; Acoustic waves; Acoustics; Alfven waves; auroral electron acceleration; Auroras; Coupled modes; Coupling; Electric field; Electric fields; Electron acceleration; Electrons; Ionosphere; kinetic Alfven wave; Magnetohydrodynamic waves; Magnetospheres; modified electron acoustic wave; Simulation; Sound waves; Voltage drop
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL102680

Results from a 1D kinetic simulation, for the first time, reveal the important role of modified electron acoustic wave (MEAW) in auroral electron acceleration. Parallel electric fields, generated due to the mode coupling between kinetic Alfven waves (KAWs) and MEAWs in the transition region from the magnetosphere and the ionosphere, can be sustained by continuous energy input carried by Alfven waves from the magnetosphere. Under the incidence of long‐period Alfven waves carrying upward field‐aligned currents, a parallel potential drop can be formed in the transition region, leading to mono‐energetic electron acceleration. Such a mechanism provides a possible link between shear Alfven waves and the mesoscale mono‐energetic auroral electron acceleration. Plain Language Summary Discrete aurora is supposed to be caused by precipitated electrons accelerated by parallel electric field. The mode coupling between modified electron acoustic waves (MEAWs), which received little attention, and kinetic Alfven waves is an effective mechanism of the generation of parallel electric field. The present simulation results show that the generation of parallel electric field, due to the mode coupling in the transition region, could be important or even dominant under certain circumstances. Our findings point out the importance of the MEAWs on the auroral electron acceleration. Key Points Simulation results indicate that modified electron acoustic waves (MEAWs) strongly affect the auroral electron acceleration Kinetic Alfven waves under certain circumstances lead to mono‐energetic acceleration through mode coupling to MEAWs Such a mechanism provides a possible link between Alfven waves and mono‐energetic electron acceleration