The Role of Tectonic Plate Thickness and Mantle Conductance in Determining Regional Vulnerability to Extreme Space Weather Events: Possible Enhancement of Magnetic Source Fields by Secondary Induction in the Asthenosphere
The Role of Tectonic Plate Thickness and Mantle Conductance in Determining Regional Vulnerability to Extreme Space Weather Events: Possible Enhancement of Magnetic Source Fields by Secondary Induction in the Asthenosphere
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DOI：
10.1029/2020sw002587
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
F. Simpson;K. Bahr
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文献类型：
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作者：
F. Simpson;K. Bahr
在磁暴期间，太阳-磁层-电离层-地球的相互作用会在电网、天然气管道和铁路网等人造技术导体中产生地磁感应电流(GIC)，并可能造成破坏性后果。一般来说，地球的导电区域比电阻区域对GIC的风险更小，因为与GIC相关的感应电场通过地球的阻抗与给定的磁源场线性相关。在这里，我们表明，与风暴有关的磁源场可以通过地球导电软流层中的二次电磁(EM)感应来增强，并且这种以前被忽视的效应可以在软流层电导较高的地区产生靠近岩石圈-软流圈边界的更大电场。我们对2003年10月30日“万圣节”和2017年9月8日风暴的数据分析表明，这两个风暴的电场大小都受到岩石圈板块厚度和软流层电导(电导率-厚度乘积)的影响，瑞典南部的电场强度是苏格兰中部的5倍(2003年10月30日“万圣节”风暴的电场强度为5V/公里)。我们的结果为我们提供了洞察为什么瑞典在2003年经历了与风暴相关的停电，而苏格兰没有。
During magnetic storms, solar‐magnetosphere‐ionosphere‐Earth interactions give rise to geomagnetically induced currents (GICs) in man‐made technological conductors such as power grids, gas pipelines, and railway networks with potentially damaging outcomes. Generally, electrically conductive regions of the Earth are assumed to be less at risk to GICs than resistive ones, since induced electric fields associated with GICs are linearly related to given magnetic source fields via Earth's impedance. Here, we show that magnetic source fields associated with storms can be enhanced by secondary electromagnetic (EM) induction in Earth's electrically conductive asthenosphere and that this previously neglected effect can give rise to larger electric fields close to the lithosphere‐asthenosphere boundary in regions where the conductance of the asthenosphere is higher. Our analysis of data from the 30 October 2003 “Halloween” and 8 September 2017 storms shows that the magnitudes of electric fields from both storms are affected by lithospheric plate thickness and asthenosphere conductance (conductivity‐thickness product) and that they are 5 times larger in southern Sweden (>5 V/km for the 30 October 2003 “Halloween” storm) than in central Scotland. Our results provide insight into why Sweden experienced a storm‐related power outage in 2003, whereas Scotland did not.