Nighttime Magnetic Perturbation Events Observed in Arctic Canada: 1. Survey and Statistical Analysis
Nighttime Magnetic Perturbation Events Observed in Arctic Canada: 1. Survey and Statistical Analysis
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DOI：
10.1029/2019ja026794
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
Mark J. Engebretson;V. Pilipenko;L. Ahmed;J. Posch;E. Steinmetz;M. Moldwin;Martin G. Connors
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文献类型：
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作者：
Mark J. Engebretson;V. Pilipenko;L. Ahmed;J. Posch;E. Steinmetz;M. Moldwin;Martin G. Connors
与大的、孤立的、振幅的磁扰动有关的磁场的快速变化|ΔB|数百纳特斯拉和5至10分钟的周期可以引起地磁感应电流的爆发，这可能会损害技术系统。本文介绍了2014年至2017年在加拿大北极东部观测到的夜侧磁扰动事件特征的统计总结，使用的数据来自四个磁强计阵列的一部分：MACCS，AUTUMNX，CANMOS和CARISMA，覆盖磁纬度范围从68到78°。大多数但不是所有的磁扰动事件都与亚暴有关：大约三分之二发生在开始后5到30分钟之间。在73°以上的纬度地区，强烈的夜间磁扰动事件与磁暴的关联明显减少，大概在名义上的极光椭圆上方。对多塞特角21个强事件的叠加时代研究表明，|DB/DT|值出现在~275 km半径内，与向上和向下场向电流之间的剪切区域相关。脉冲幅度的统计分布，|ΔB|和|DB/DT|在所有站点拟合良好的对数正态分布。的|ΔB|分布是类似的磁纬度范围内的研究，但峰度和偏度的|DB/DT|分布随纬度略有增加。对这些事件的统计特征的了解使我们能够使用对数正态分布的近似来估计极端脉冲扰动的发生概率。
The rapid changes of magnetic fields associated with large, isolated magnetic perturbations with amplitudes |ΔB| of hundreds of nanotesla and 5‐ to 10‐min periods can induce bursts of geomagnetically induced currents that can harm technological systems. This paper presents statistical summaries of the characteristics of nightside magnetic perturbation events observed in Eastern Arctic Canada from 2014 through 2017 using data from stations that are part of four magnetometer arrays: MACCS, AUTUMNX, CANMOS, and CARISMA, covering a range of magnetic latitudes from 68 to 78°. Most but not all of the magnetic perturbation events were associated with substorms: roughly two thirds occurred between 5 and 30 min after onset. The association of intense nighttime magnetic perturbation events with magnetic storms was significantly reduced at latitudes above 73°, presumably above the nominal auroral oval. A superposed epoch study of 21 strong events at Cape Dorset showed that the largest |dB/dt| values appeared within an ~275‐km radius that was associated with a region of shear between upward and downward field‐aligned currents. The statistical distributions of impulse amplitudes of both |ΔB| and |dB/dt| fit well the log‐normal distribution at all stations. The |ΔB| distributions are similar over the magnetic latitude range studied, but the kurtosis and skewness of the |dB/dt| distributions show a slight increase with latitude. Knowledge of the statistical characteristics of these events has enabled us to estimate the occurrence probability of extreme impulsive disturbances using the approximation of a log‐normal distribution.