The Density of the Earth's Cusp Region: Three-Dimensional Distribution, Formation, and Influencing Factors

IF 2.6 2区 地球科学 Q2 ASTRONOMY & ASTROPHYSICS
Tieyan Wang, Chao Xiao, Wenhao Chen, Xiaoxiao Qin, Xiangcheng Dong, Ganming Ren, Hongtao Huang, Die Duan, Yin Xu
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Abstract

The Earth's magnetospheric cusp region is an important pathway for solar wind particles entering the magnetosphere and ionospheric ions escaping. The plasma density is a key parameter for understanding this physical process. Based on measurements from the Cluster-3 spacecraft (2001–2010), we selected 878 cusp crossing events (470 in the northern and 408 in the southern hemisphere) and statistically studied the three-dimensional distribution of cusp ion density, its causes, and influencing factors. Our analysis revealed that cusp density is highest at MLT = 12 and decreases as MLT moves away from 12 in both hemispheres; in Solar Magnetic coordinates, the maximum density occurs near the equatorward boundary in the X direction, while in the Z direction, the density shows slight changes. This feature may be largely influenced by the inhomogeneity of magnetic pressure. Furthermore, we found that as the dominant source, solar wind ions enter the cusp effectively near noon and diffuses toward dawn and dusk; the polar ionosphere source becomes important with increasing AE index, transporting particles from a wide MLT range to the cusp; and the dipole tilt angle significantly affects cusp density.

地球尖端区的密度:三维分布、形成和影响因素
地球磁层尖区是太阳风粒子进入磁层和电离层离子逸出的重要通道。等离子体密度是理解这一物理过程的关键参数。基于Cluster-3航天器2001-2010年的观测数据,选取878次尖峰穿越事件(北半球470次,南半球408次),统计研究了尖峰离子密度的三维分布、产生原因和影响因素。我们的分析表明,在MLT = 12时,两个半球的尖端密度最高,随着MLT远离12而降低;在太阳磁坐标中,X方向上的密度最大值出现在赤道边界附近,而在Z方向上,密度变化不大。这种特性很大程度上受磁压不均匀性的影响。此外,我们还发现,太阳风离子作为优势源,在中午附近有效地进入尖端,并向黎明和黄昏扩散;随着声发射指数的增加,极地电离层源变得重要,将粒子从较宽的MLT范围输送到尖端;偶极子倾斜角度对尖峰密度有显著影响。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Geophysical Research: Space Physics
Journal of Geophysical Research: Space Physics Earth and Planetary Sciences-Geophysics
CiteScore
5.30
自引率
35.70%
发文量
570
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