Comparative Study of Super Substorms During Geomagnetic Storm Time and Non-storm Time
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摘要: 磁层亚暴作为太阳风-磁层-电离层耦合的一种基本模式,对近地空间环境有着深远影响。超强亚暴是指暴时AE或SME指数最大值超过2000 nT的亚暴,相较于一般强度的亚暴有着更强的能量注入过程和不同的响应模式。本文基于现有的亚暴列表,选取太阳风条件类似的两个分别处于磁暴期间与非磁暴期间的超强亚暴案例,利用地球同步轨道卫星LNAL与GOES的实地观测数据、OMNI与SuperMAG的极光电集流与环电流参数以及CIMI模型的模拟结果从空间环境、能量运输与环电流的角度对两案例进行了对比分析。结果表明:(1)磁暴期间的超强亚暴信号传播可能比非磁暴期间的超强亚暴信号传播距离短,这主要是因为背景等离子体环境不同导致的;(2)非磁暴期间超强亚暴SME指数在地方时上出现明显的双峰结构;(3)磁暴的出现会造成氧离子的增强,使得超强亚暴期间环电流更强。通过对磁暴期间和非磁暴期间超强亚暴异同点的研究,可以更深入的理解超强亚暴的作用过程和影响机制、超强亚暴与磁暴之间的联系,进一步推动对空间天气与日地空间环境的认识。Abstract: As a fundamental coupling mode between the solar wind, magnetosphere, and ionosphere, substorms have profound impacts on the near-Earth space environment. Super substorms refer to those during which the maximum value of AE or SME index exceeds 2000 nT, featuring stronger energy injection processes and different response modes compared with normal substorms. In this study, based on an existing substorm list, we selected two cases of super substorms with similar solar wind conditions—one occurring during a geomagnetic storm and the other during a non-storm period. Using in-situ observation data from geosynchronous orbit satellites LNAL and GOES, auroral electrojet and ring current parameters from OMNI and SuperMAG, as well as numerical simulation results from the CIMI model, we conduct comparative analysis of these two cases from the perspectives of particle injection, energy input, and ring current dynamics. The results show that: (1) During geomagnetic storms, the propagation distance of super substorm signals may be shorter than that during non-storm periods, primarily due to differences in the background plasma environment; (2) During non-storm periods, the SME index of super substorms exhibits a distinct bimodal structure as a function of local time; (3) The occurrence of geomagnetic storms leads to enhanced oxygen ion flux, thereby intensifying the ring current during super substorms. By studying the similarities and differences between super substorms during and outside of geomagnetic storms, this research can better serve future studies on the physical processes and impact mechanisms of super substorms, as well as the relationship between super substorms and geomagnetic storms, further promoting the understanding of space weather and the Earth-space environment.
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Key words:
- Super substorm /
- Geomagnetic storm /
- Auroral electrojet /
- Ring current
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