| 2005年8月24日磁暴主相期间亚暴过程的多卫星联合观测分析 |
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| 引用本文： | 孙晓英,段素平,刘维宁.2005年8月24日磁暴主相期间亚暴过程的多卫星联合观测分析[J].地球物理学报,2014,57(11):3729-3745. |
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| 作者姓名： | 孙晓英 段素平 刘维宁 |
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| 作者单位： | 1. 中国科学院空间科学与应用研究中心, 北京 100190;
2. 中国科学院大学, 北京 100049 |
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| 基金项目： | 国家自然科学基金(40974099)和国家重点实验室专项基金项目资助. |
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| 摘 要： | 本文根据OMNI、TC-2卫星、LANL系列卫星、Cluster星簇卫星(C1-C4)以及加拿大的8个中高纬地磁台站的观测数据,研究了2005年8月24日强磁暴(SYM-Hmin~ -179 nT)主相期间的强亚暴(ALmin~ -4046 nT)事件特征.该强磁暴在大振幅(IMF Bz min~ -55.57 nT)、短持续时间(~90 min)的行星际磁场条件下产生,有明显的磁暴急始(SSC),强度较大且持续时间较短.发生在磁暴主相期间的亚暴发展的主要特征如下:亚暴增长相期间,C1-C4卫星先后穿越中心等离子体片;亚暴膨胀相触发后,在近地磁尾(X~-6RE)可观测到磁场偶极化现象;等离子体无色散注入区在亚暴onset开始后迅速沿经向扩展,但被限制在有限的经度范围;磁纬60°附近,Pi2地磁脉动振幅超过了100 nT.膨胀相开始后,在中、高磁纬地磁台站可观测到负湾扰,近地磁尾可观测到Pi2空间脉动,中磁尾区域可观测到尾向流、磁重联以及O+/H+数密度比值在亚暴onset之后增大等现象.分析表明该强磁暴主相期间的强亚暴现象发生时序是自内向外:X~-6RE处TC-2观测到磁场偶极化(~09:42:30 UT),同步轨道卫星LANL1994-084观测到等离子体无色散注入(~09:44:30 UT),X~-17.8RE处C1观测到磁场重联(~09:45:30 UT),由此推断该亚暴事件很可能是近地磁尾不稳定性触发产生,其发生区域距离地球很近.
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| 关 键 词： | 磁暴 亚暴 磁场偶极化 等离子体无色散注入 Pi2地磁脉动 |
| 收稿时间： | 2014-07-03 |
Multi-satellite joint observations of an intense substorm during the main phase of 24 August, 2005 storm |
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| SUN Xiao-Ying,DUAN Su-Ping,LIU W. W.Multi-satellite joint observations of an intense substorm during the main phase of 24 August, 2005 storm[J].Chinese Journal of Geophysics,2014,57(11):3729-3745. |
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| Authors: | SUN Xiao-Ying DUAN Su-Ping LIU W W |
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| Institution: | 1. National Space Science Center (NSSC), Chinese Academy of Sciences (CAS), Beijing 100190, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | Observational data from OMNI, TC-2, LANL series of satellites, Cluster(C1—C4) and Canada's eight mid- and high-magnetic latitude geomagnetic stations are used to investigate the features of the intense substorm (ALmin~-4046 nT) during the main phase of the 24 August, 2005 storm (SYM-Hmin~-179 nT). The intense storm that occurred on 24 August, 2005 was driven by the interplanetary magnetic field with significantly negative Bz (IMF Bz min~-55.57 nT), with a comparatively short duration (~90 min). It had a significant storm sudden commence (SSC) and great intensity. The features of the intense substorm occurred during the main phase of the intense storm: during the growth phase, C1—C4 satellites were passing through the central plasma sheet. After expansion phase onset,in the near magnetotail (X~-6RE), magnetic field polarization was observed. Dispersionless Plasma injection zone extended rapidly along the longitude direction after the substorm onset, but was restricted to a limited longitude range. Near magnetic latitude 60°, the oscillation intensity of Pi2 geomagnetic pulsation was over 100 nT. After expansion phase onset, the mid- and high-magnetic latitude geomagnetic stations observed negative bays; in the near-Earth magnetotail, TC-2 observed Pi2 pulsations; in the mid-magnetotail, tailward flow and magnetic reconnection was observed and the ratio of O+/H+ number density increased. Observational results show that the timing of the features of the intense substorm which occurred in the main phase of the intense storm was inside-out: at ~09:42:30 UT, TC-2 observed magnetic field polarization at X~-6RE; at ~09:43:30 UT, LANL1994-084 observed Plasma dispersionless injection; at ~09:45:30 UT, Cluster-1 observed magnetic reconnection at X~-17.8RE. Therefore, we inferred that this substorm event was likely to be triggered by some instabilities occurring in the near-Earth magnetotail, and its triggering region was quite close to the Earth. |
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| Keywords: | Magnetic storms Substorms Magnetic dipolarization Dispersionless Plasma injection Pi2 geomagnetic pulsations |
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