Geospace Plume and Its Impact on Dayside Magnetopause Reconnection Rate.
Geospace Plume and Its Impact on Dayside Magnetopause Reconnection Rate.
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地球空间羽流及其对日侧磁层顶重联率的影响。
DOI：
10.1029/2021ja029117
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
Henderson MG
中科院分区：
文献类型：
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作者：
Zou Y;Walsh BM;Shi X;Lyons L;Liu J;Angelopoulos V;Ruohoniemi JM;Coster AJ;Henderson MG
地球空间羽流在影响磁层顶重联效率方面的作用是一个悬而未决的问题，有两种对立的理论正在争论。局部控制理论认为，羽流会降低局部和全局的重连率，而全局控制理论则认为，全局重连率是由太阳风控制的，而不是由局部物理控制的。在观测上，有限数量的航天器点测量无法揭示局部变化是否影响全球重联。因此，需要一个分布式观测站来评估这两个理论的有效性。我们使用THEMIS和洛斯阿拉莫斯国家实验室的航天器来确定地球空间羽流的发生及其与磁层顶的接触。全球演变和形态的羽使用GPS测量跟踪。然后，SuperDARN被用来监测昼侧重联的分布和强度。两个风暴时间的地球空间羽流事件进行了检查，并表明，作为羽流接触磁层顶，重联的效率降低在接触经度。两次事件的局部减少量分别为81%和68%，这两个值与羽流的质量负荷效应一致，如果羽流的原子质量为104 amu。当太阳风驱动稳定时，跨极帽势变化不大。这项研究阐明了解决冷稠密等离子体对太阳风-磁层耦合作用的途径，观测结果表明，羽流重新分配磁层顶重联活动，而不会显著改变全球强度。我们战略性地协调THEMIS和洛斯阿拉莫斯国家实验室航天器、GPS网络和SuperDARN进行的测量，以调查地球空间羽流。羽流降低了羽流经度处的局部重连率，并增加了羽流附近区域的重连率。当太阳风稳定时，全球重连在羽流存在时保持不变，支持全球控制理论。
The role a geospace plume in influencing the efficiency of magnetopause reconnection is an open question with two contrasting theories being debated. A local‐control theory suggests that a plume decreases both local and global reconnection rates, whereas a global‐control theory argues that the global reconnection rate is controlled by the solar wind rather than local physics. Observationally, limited numbers of point measurements from spacecraft cannot reveal whether a local change affects the global reconnection. A distributed observatory is hence needed to assess the validity of the two theories. We use THEMIS and Los Alamos National Laboratory spacecraft to identify the occurrence of a geospace plume and its contact with the magnetopause. Global evolution and morphology of the plume is traced using GPS measurements. SuperDARN is then used to monitor the distribution and the strength of dayside reconnection. Two storm‐time geospace plume events are examined and show that as the plume contacts the magnetopause, the efficiency of reconnection decreases at the contact longitude. The amount of local decrease is 81% and 68% for the two events, and both values are consistent with the mass loading effect of the plume if the plume's atomic mass is ∼4 amu. Reconnection in the surrounding is enhanced, and when the solar wind driving is stable, little variation is seen in the cross polar cap potential. This study illuminates a pathway to resolve the role of cold dense plasma on solar wind‐magnetosphere coupling, and the observations suggest that plumes redistribute magnetopause reconnection activity without changing the global strength substantially. We strategically coordinate measurements made by THEMIS and Los Alamos National Laboratory spacecraft, GPS network, and SuperDARN to investigate geospace plumes Plumes decrease the local reconnection rate at the plume longitude and increase the reconnection rate in regions adjacent to the plume When the solar wind is stable, the global reconnection remains unchanged in presence of plumes, supporting a global‐control theory