Variability of the pitch angle distribution of radiation belt ultrarelativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations
文献类型：期刊论文
| 作者 | Ni, Binbin; Zou, Zhengyang; Gu, Xudong; Zhou, Chen; Thorne, Richard M.; Bortnik, Jacob; Shi, Run; Zhao, Zhengyu; Baker, Daniel N.; Kanekal, Shrikhanth G. |
| 刊名 | JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
 |
| 出版日期 | 2015 |
| 卷号 | 120期号:6页码:4863-4876 |
| 关键词 | radiation belt ultrarelativistic electrons pitch angle distribution decay time scales geomagnetic storms resonant wave-particle interactions |
| ISSN号 | 2169-9380 |
| 通讯作者 | Ni, BB (reprint author), Wuhan Univ, Sch Elect Informat, Dept Space Phys, Wuhan 430072, Peoples R China. |
| 英文摘要 | Fifteen months of pitch angle resolved Van Allen Probes Relativistic Electron-Proton Telescope (REPT) measurements of differential electron flux are analyzed to investigate the characteristic variability of the pitch angle distribution of radiation belt ultrarelativistic (>2MeV) electrons during storm conditions and during the long-term poststorm decay. By modeling the ultrarelativistic electron pitch angle distribution as sin(n)alpha, where alpha is the equatorial pitch angle, we examine the spatiotemporal variations of the n value. The results show that, in general, n values increase with the level of geomagnetic activity. In principle, ultrarelativistic electrons respond to geomagnetic storms by becoming more peaked at 90 degrees pitch angle with n values of 2-3 as a supportive signature of chorus acceleration outside the plasmasphere. High n values also exist inside the plasmasphere, being localized adjacent to the plasmapause and exhibiting energy dependence, which suggests a significant contribution from electromagnetic ion cyclotron (EMIC) wave scattering. During quiet periods, n values generally evolve to become small, i.e., 0-1. The slow and long-term decays of the ultrarelativistic electrons after geomagnetic storms, while prominent, produce energy and L-shell-dependent decay time scales in association with the solar and geomagnetic activity and wave-particle interaction processes. At lower L shells inside the plasmasphere, the decay time scales tau(d) for electrons at REPT energies are generally larger, varying from tens of days to hundreds of days, which can be mainly attributed to the combined effect of hiss-induced pitch angle scattering and inward radial diffusion. As L shell increases to L similar to 3.5, a narrow region exists (with a width of similar to 0.5L), where the observed ultrarelativistic electrons decay fastest, possibly resulting from efficient EMIC wave scattering. As L shell continues to increase, tau(d) generally becomes larger again, indicating an overall slower loss process by waves at high L shells. Our investigation based upon the sin(n)alpha function fitting and the estimate of decay time scale offers a convenient and useful means to evaluate the underlying physical processes that play a role in driving the acceleration and loss of ultrarelativistic electrons and to assess their relative contributions. |
| 收录类别 | SCI |
| 语种 | 英语 |
| 源URL | [http://ir.nssc.ac.cn/handle/122/4606]  |
| 专题 | 国家空间科学中心_空间科学部 |
| 推荐引用方式 GB/T 7714 | Ni, Binbin,Zou, Zhengyang,Gu, Xudong,et al. Variability of the pitch angle distribution of radiation belt ultrarelativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,2015,120(6):4863-4876. |
| APA | Ni, Binbin.,Zou, Zhengyang.,Gu, Xudong.,Zhou, Chen.,Thorne, Richard M..,...&Li, Xinlin.(2015).Variability of the pitch angle distribution of radiation belt ultrarelativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations.JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,120(6),4863-4876. |
| MLA | Ni, Binbin,et al."Variability of the pitch angle distribution of radiation belt ultrarelativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations".JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 120.6(2015):4863-4876. |
入库方式： OAI收割
来源：国家空间科学中心
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