Evidence of kinetic Alfvén eigenmode in the near-Earth magnetotail during substorm expansion phase

	Evidence of kinetic Alfvén eigenmode in the near-Earth magnetotail during substorm expansion phase
	S. P. Duan; Lei Dai; Chi Wang; J. Liang; A. T. Y. Lui; L. J. Chen; Z. H. He; Y. C. Zhang; V. Angelopoulos
刊名	Journal of Geophysical Research: Space Physics
	2016
关键词	kinetic Alfvén wave substorm Hall current aurora brightening Hall fields
ISSN号	0148-0227
英文摘要	Unipolar pulses of kinetic Alfvén waves (KAW) are first observed in the near-Earth plasma sheet (NEPS) associated with dipolarizations during substorm expansion phases. Two similar events are studied with Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations during substorms on 3 February 2008 and 7 February 2008. The unipolar pulses were located at a trough-like Alfvén speed profile in the northern plasma sheet at a distance of 10–11 R_Efrom Earth. The dominant wave components consist of a southward δE_z toward the neutral plane and a +δB_y toward the dusk. The \|δE_z\|/\|δB_y\| ratio was in the range of a few times the local Alfvén speed, a strong indication of KAW nature. The wave Poynting flux was earthward and nearly parallel to the background magnetic field. The pulse was associated with an earthward field-aligned current carried by electrons. These observational facts strongly indicate a KAW eigenmode that is confined by the plasma sheet but propagates earthward along the field line. The KAW eigenmode was accompanied by short timescale (1 min) dipolarizations likely generated by transient magnetotail reconnection. The observed polarity of the KAW field/current is consistent with that of the Hall field/current in magnetic reconnection, supporting the scenario that the Hall fields/current propagate out from reconnection site as KAW eigenmodes. Aurora images on the footprint of THEMIS spacecraft suggest that KAW eigenmode may power aurora brightening during substorm expansion phase.
收录类别	SCI
语种	英语
内容类型	期刊论文
源URL	[http://ir.nssc.ac.cn/handle/122/5425]
专题	国家空间科学中心_空间科学部
推荐引用方式 GB/T 7714	S. P. Duan,Lei Dai,Chi Wang,et al. Evidence of kinetic Alfvén eigenmode in the near-Earth magnetotail during substorm expansion phase[J]. Journal of Geophysical Research: Space Physics,2016.
APA	S. P. Duan.,Lei Dai.,Chi Wang.,J. Liang.,A. T. Y. Lui.,...&V. Angelopoulos.(2016).Evidence of kinetic Alfvén eigenmode in the near-Earth magnetotail during substorm expansion phase.Journal of Geophysical Research: Space Physics.
MLA	S. P. Duan,et al."Evidence of kinetic Alfvén eigenmode in the near-Earth magnetotail during substorm expansion phase".Journal of Geophysical Research: Space Physics (2016).