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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
Space Weather ( IF 4.288 ) Pub Date : 2020-11-09 , DOI: 10.1029/2020sw002587
Fiona Simpson 1 , Karsten Bahr 2
Affiliation  

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.

中文翻译:

构造板厚和地幔电导在确定极端空间天气事件的区域脆弱性中的作用:通过软流圈的二次感应可能增强磁场源

在磁暴期间,太阳-磁层-电离层-地球的相互作用会在人造技术导体(例如电网,天然气管道和铁路网络)中产生地磁感应电流(GIC),从而可能造成破坏性后果。通常,由于与GIC相关的感应电场通过地球的阻抗与给定的磁场线性相关,因此,假定地球的导电区域对GIC的威胁要比电阻区域小。在这里,我们表明,与风暴相关的磁场可以通过地磁中的次级电磁感应来增强 导电的软流圈,并且这种先前被忽略的效应会在软流圈电导率较高的区域中靠近岩石圈-软流圈边界处产生更大的电场。我们对2003年10月30日“万圣节”风暴和2017年9月8日风暴数据的分析表明,两次风暴的电场强度均受岩石圈板厚度和软流圈电导率(电导率-厚度积)的影响,在大范围内是5倍。瑞典南部(2003年10月30日“万圣节”暴风雨> 5 V / km)比苏格兰中部大。我们的结果提供了有关瑞典为何在2003年经历与风暴有关的电力中断而苏格兰却没有的原因的见解。我们对2003年10月30日“万圣节”风暴和2017年9月8日风暴的数据分析表明,两次风暴的电场强度均受岩石圈板厚度和软流圈电导率(电导率-厚度积)的影响,在大范围内,它们的大小要大5倍。瑞典南部(2003年10月30日“万圣节”暴风雨> 5 V / km)比苏格兰中部大。我们的结果提供了有关瑞典为何在2003年经历与风暴有关的电力中断而苏格兰却没有的原因的见解。我们对2003年10月30日“万圣节”风暴和2017年9月8日风暴数据的分析表明,两次风暴的电场强度均受岩石圈板厚度和软流圈电导率(电导率-厚度积)的影响,在大范围内是5倍。瑞典南部(2003年10月30日“万圣节”暴风雨> 5 V / km)比苏格兰中部大。我们的结果提供了关于为什么瑞典在2003年经历与风暴有关的电力中断而苏格兰却没有的原因的见解。
更新日期:2020-12-24
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