Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB / dt Events at High Latitudes
Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB / dt Events at High Latitudes
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高纬度地区大 dB/dt 事件发生的太阳周期和太阳风依赖性
DOI：
10.1029/2022ja030953
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Gjerloev, J.
中科院分区：
文献类型：
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作者：
Milan, S. E.;Imber, S. M.;Fleetham, A. L.;Gjerloev, J.
我们研究了磁场的急剧变化，这种变化会产生地磁感应电流（GIC），从而损坏管道和电网。我们使用一分钟节奏的SuperMAG观测来寻找磁场“尖峰”的发生分布。最近的研究确定了极端事件的重现统计数据，并绘制了峰值的当地时间分布图;然而，人们对它们与太阳活动和太阳风条件的关系知之甚少。我们研究了太阳活动周期23和24，大约1995年至2020年期间的尖峰发生。我们发现了三个当地时间的热点：与亚暴爆发相关的午夜前区域，通常与欧米茄波段活动相关的黎明扇区，以及与磁层顶发生的开尔文-亥姆霍兹不稳定性（KHI）相关的中午前扇区。亚暴和KHI的磁场扰动主要是南北向的，欧米茄带的磁场扰动主要是东西向的。亚暴尖峰出现在太阳活动周期的各个阶段，但在下降阶段达到最大值。欧米茄波段和KHI尖峰仅限于太阳极大期和下降阶段。亚暴峰值出现在中等太阳风驱动期间，欧米茄带峰值出现在强烈驱动期间，KHI峰值出现在安静条件下但具有高太阳风速度。我们表明，这些分布的形状不依赖于尖峰的大小，所以似乎我们的结果可以外推到极端事件。
We investigate sharp changes in magnetic field that can produce Geomagnetically Induced Currents (GICs) which damage pipelines and power grids. We use one‐minute cadence SuperMAG observations to find the occurrence distribution of magnetic field “spikes.” Recent studies have determined recurrence statistics for extreme events and charted the local time distribution of spikes; however, their relation to solar activity and conditions in the solar wind is poorly understood. We study spike occurrence during solar cycles 23 and 24, roughly 1995 to 2020. We find three local time hotspots in occurrence: the pre‐midnight region associated with substorm onsets, the dawn sector often associated with omega band activity, and the pre‐noon sector associated with the Kelvin‐Helmholtz instability (KHI) occurring at the magnetopause. Magnetic field perturbations are mainly North‐South for substorms and KHI, and East‐West for omega bands. Substorm spikes occur at all phases of the solar cycle, but maximize in the declining phase. Omega‐band and KHI spikes are confined to solar maximum and the declining phase. Substorm spikes occur during moderate solar wind driving, omega band spikes during strong driving, and KHI spikes during quiet conditions but with high solar wind speed. We show that the shapes of these distributions do not depend on the magnitude of the spikes, so it appears that our results can be extrapolated to extreme events.