Resonant scattering of outer zone relativistic electrons by multiband   EMIC waves and resultant electron loss time scales

doi:10.1002/2015JA021466

CORC > 北京大学 > 地球与空间科学学院

	Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales
	Ni, Binbin ; Cao, Xing ; Zou, Zhengyang ; Zhou, Chen ; Gu, Xudong ; Bortnik, Jacob ; Zhang, Jichun ; Fu, Song ; Zhao, Zhengyu ; Shi, Run ; Xie, Lun
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
	2015
关键词	outer radiation belt EMIC waves relativistic electrons resonant wave-particle interactions electron loss time scales ION-CYCLOTRON WAVES LINEAR DIFFUSION-COEFFICIENTS 1-2 MAGNETIC PULSATIONS PITCH-ANGLE SCATTERING VAN ALLEN PROBES GEOMAGNETIC STORMS EQUATORIAL MAGNETOSPHERE ELECTROMAGNETIC-WAVES RADIATION BELT 30 SEPTEMBER
DOI	10.1002/2015JA021466
英文摘要	To improve our understanding of the role of electromagnetic ion cyclotron (EMIC) waves in radiation belt electron dynamics, we perform a comprehensive analysis of EMIC wave-induced resonant scattering of outer zone relativistic (>0.5MeV) electrons and resultant electron loss time scales with respect to EMIC wave band, L shell, and wave normal angle model. The results demonstrate that while H+-band EMIC waves dominate the scattering losses of similar to 1-4MeV outer zone relativistic electrons, it is He+-band and O+-band waves that prevail over the pitch angle diffusion of ultrarelativistic electrons at higher energies. Given the wave amplitude, EMIC waves at higher L shells tend to resonantly interact with a larger population of outer zone relativistic electrons and drive their pitch angle scattering more efficiently. Obliquity of EMIC waves can reduce the efficiency of wave-induced relativistic electron pitch angle scattering. Compared to the frequently adopted parallel or quasi-parallel model, use of the latitudinally varying wave normal angle model produces the largest decrease in H+-band EMIC wave scattering rates at pitch angles similar to 5MeV. At a representative nominal amplitude of 1nT, EMIC wave scattering produces the equilibrium state (i.e., the lowest normal mode under which electrons at the same energy but different pitch angles decay exponentially on the same time scale) of outer belt relativistic electrons within several to tens of minutes and the following exponential decay extending to higher pitch angles on time scales from <1min to similar to 1h. The electron loss cone can be either empty as a result of the weak diffusion or heavily/fully filled due to approaching the strong diffusion limit, while the trapped electron population at high pitch angles close to 90 degrees remains intact because of no resonant scattering. In this manner, EMIC wave scattering has the potential to deepen the anisotropic distribution of outer zone relativistic electrons by reshaping their pitch angle profiles to top-hat. Overall, H+-band and He+-band EMIC waves are most efficient in producing the pitch angle scattering loss of relativistic electrons at similar to 1-2MeV. In contrast, the presence of O+-band EMIC waves, while at a smaller occurrence rate, can dominate the scattering loss of 5-10MeV electrons in the entire region of the outer zone, which should be considered in future modeling of the outer zone relativistic electron dynamics.; NSFC [41204120, 41474141]; Fundamental Research Funds for the Central Universities [2042014kf0251]; NASA [NNX11AO82G, NNX15AF66G, NNX14AN85G, NNX13AI61G]; SCI(E); ARTICLE; bbni@whu.edu.cn; 9; 7357-7373; 120
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/416465]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Ni, Binbin,Cao, Xing,Zou, Zhengyang,et al. Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,2015.
APA	Ni, Binbin.,Cao, Xing.,Zou, Zhengyang.,Zhou, Chen.,Gu, Xudong.,...&Xie, Lun.(2015).Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales.JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS.
MLA	Ni, Binbin,et al."Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales".JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS (2015).