Interhemispheric Asymmetries in the Ground Magnetic Response to Interplanetary Shocks: The Role of Shock Impact Angle
Interhemispheric Asymmetries in the Ground Magnetic Response to Interplanetary Shocks: The Role of Shock Impact Angle
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DOI：
10.1029/2019sw002427
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
Z. Xu;M. Hartinger;D. Oliveira;S. Coyle;C. Clauer;D. Weimer;T. Edwards
中科院分区：
文献类型：
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作者：
Z. Xu;M. Hartinger;D. Oliveira;S. Coyle;C. Clauer;D. Weimer;T. Edwards
行星际（IP）冲击驱动磁层-电离层（MI）电流系统，而这些电流系统又与地面磁扰动有关。最近的研究表明，IP冲击的影响角度在控制随后的地磁活动和磁扰动方面起着重要作用;例如，由于半球间不对称的磁层压缩，高度倾斜的冲击会驱动不对称的MI响应，而几乎是迎头冲击会驱动更对称的MI响应。然而，很少有观测证实倾斜冲击驱动高纬度地磁响应中的这种不对称性。我们使用来自南极磁力计链的数据，结合格陵兰岛西海岸的磁共轭站，来测试这些模型预测（Oliveira & Raeder，2015，https：//doi.org/10.1002/2015JA021147; Oliveira，2017，https：//doi.org/10.1007/s13538-016-0472-x）。我们分别计算了每个半球的磁场的时间导数（B/t）。接下来，我们检查北方到南半球的最大强度B/最大强度之间的时间差的IP冲击的影响，最大强度B/最大强度之间的比率。我们根据从最近发表的数据库中获得的冲击冲击角度对这些结果进行了排序，其中包含500多个事件，并讨论了冲击角度如何影响地面磁响应中的南北半球不对称性。我们发现，首先受到冲击的半球通常有（1）最先的反应是B/t，（2）最强烈的反应是B/t。此外，我们表明，高度倾斜的冲击可以产生高纬度地面磁响应，这与基于假设对称驾驶条件的模型的预测有很大不同。
Interplanetary (IP) shocks drive magnetosphere‐ionosphere (MI) current systems that in turn are associated with ground magnetic perturbations. Recent work has shown that IP shock impact angle plays a significant role in controlling the subsequent geomagnetic activity and magnetic perturbations; for example, highly inclined shocks drive asymmetric MI responses due to interhemispherical asymmetric magnetospheric compressions, while almost head‐on shocks drive more symmetric MI responses. However, there are few observations confirming that inclined shocks drive such asymmetries in the high‐latitude ground magnetic response. We use data from a chain of Antarctic magnetometers, combined with magnetically conjugate stations on the west coast of Greenland, to test these model predictions (Oliveira & Raeder, 2015, https://doi.org/10.1002/2015JA021147; Oliveira, 2017, https://doi.org/10.1007/s13538-016-0472-x). We calculate the time derivative of the magnetic field ( ∂B/∂t ) in each hemisphere separately. Next, we examine the ratio of Northern to Southern Hemisphere ∂B/∂t intensities and the time differences between the maximum ∂B/∂t immediately following the impact of IP shocks. We order these results according to shock impact angles obtained from a recently published database with over 500 events and discuss how shock impact angles affect north‐south hemisphere asymmetries in the ground magnetic response. We find that the hemisphere the shock strikes first usually has (1) the first response in ∂B/∂t and (2) the most intense response in ∂B/∂t . Additionally, we show that highly inclined shocks can generate high‐latitude ground magnetic responses that differ significantly from predictions based on models that assume symmetric driving conditions.