Unsolved problems: Mesoscale polar cap flow channels’ structure, propagation, and effects on space weather disturbances
Unsolved problems: Mesoscale polar cap flow channels’ structure, propagation, and effects on space weather disturbances
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DOI：
10.3389/fspas.2023.1147531
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发表时间：
2023-04
期刊：
影响因子：
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通讯作者：
L. Lyons;Y. Nishimura;Jiang Liu;Y. Zou;W. Bristow;S. Yadav;E. Donovan;N. Nishitani;K. Shiokawa;K. Hosokawa
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文献类型：
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作者：
L. Lyons;Y. Nishimura;Jiang Liu;Y. Zou;W. Bristow;S. Yadav;E. Donovan;N. Nishitani;K. Shiokawa;K. Hosokawa
动态中尺度流结构移动穿过极冠的开放场线区域，然后进入夜侧等离子体片，在那里它们可以引起重要的空间天气扰动，如流光，亚暴和欧米茄带。极冠结构的持续时间很长（显然至少1.5至2小时），但它们与扰动的联系很少受到关注。因此，重要的是要揭示是什么导致这些流动增强通道，它们如何映射到磁层和磁鞘结构，以及是什么控制它们在极冠的传播和它们到达夜侧极光椭圆后的动态效应。这里提出的例子使用630 nm的极光和雷达观测，并表明，流动通道的运动可能是关键的，以确定何时何地在夜侧极光椭圆形的特定扰动将被触发，这可以包括流动通道连接到扰动的充分理解。此外，重要的是要确定极冠流动通道如何导致极光卵形内的流动通道，即，等离子体片，并确定沿沿着夜侧椭圆/等离子体片场线的条件，所述场线与进入的极帽流动通道相互作用以引起特定扰动。它也将是有趣的，以考虑与传入的极冠流动通道，包括位置，时间和类型的干扰，以及是否持续时间和干扰的扩展与流动通道的持续时间和多个流动通道的连接地磁扰动的一般性。
Dynamic mesoscale flow structures move across the open field line regions of the polar caps and then enter the nightside plasma sheet where they can cause important space weather disturbances, such as streamers, substorms, and omega bands. The polar cap structures have long durations (apparently at least ∼1½ to 2 h), but their connections to disturbances have received little attention. Hence, it will be important to uncover what causes these flow enhancement channels, how they map to the magnetospheric and magnetosheath structures, and what controls their propagation across the polar cap and their dynamic effects after reaching the nightside auroral oval. The examples presented here use 630-nm auroral and radar observations and indicate that the motion of flow channels could be critical for determining when and where a particular disturbance within the nightside auroral oval will be triggered, and this could be included for full understanding of flow channel connections to disturbances. Also, it is important to determine how polar cap flow channels lead to flow channels within the auroral oval, i.e., the plasma sheet, and determine the conditions along nightside oval/plasma sheet field lines that interact with an incoming polar cap flow channel to cause a particular disturbance. It will also be interesting to consider the generality of geomagnetic disturbances being related to connections with incoming polar cap flow channels, including the location, time, and type of disturbances, and whether the duration and expansion of disturbances are related to flow channel duration and to multiple flow channels.