There are a number of global initiatives to understand and mitigate the impacts of extreme space weather on critical infrastructure and modern society. This paper provides the results of an analysis to estimate extreme geoelectric field values for the Australian region to facilitate evaluation of Australia's power system response to extreme geomagnetic storms. Geoelectric fields are calculated using a grid of modeled magnetotelluric impedance tensors obtained from a 3‐D conductivity model of the Australian region. Statistical metrics derived from grids of geoelectric field time series are analyzed as a function of Dst index for different storm days to extrapolate geoelectric fields to extreme storm levels over a range of ground conductivity conditions. For Carrington event storm levels, geoelectric field values of 5.3 ± 3.8 V/km in the north‐south direction and 9.6 ± 4.3 V/km in the east‐west direction are expected for areas of electrically resistive rocks near coastlines that are adjacent to deep highly conductive oceans, and inland, where there are large contrasts between the electrical conductivities of different rock types across Australia. Further, geoelectric field values may change by at least an order of magnitude over the grid spacing interval of 50 km in these areas. The results of the analysis also suggest that upscaling grids of geoelectric field time series derived from an observed storm by the ratio of extreme storm Dst to the observed storm Dst are a valid approach for the Australian region that provides extreme storm scenarios for different storm morphologies.

中文翻译：

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估算澳大利亚地区的极端地电场值

有许多全球计划旨在了解和减轻极端空间天气对关键基础设施和现代社会的影响。本文提供了分析结果，以估算澳大利亚地区的极端地电场值，以方便评估澳大利亚电力系统对极端地磁暴的反应。使用从澳大利亚地区的3D电导率模型获得的建模的大地电磁阻抗张量的网格来计算地电场。从地电场时间序列的网格得出的统计指标将作为Dst的函数进行分析不同风暴日的指数，以将地电场推断为一系列地面电导率条件下的极端风暴水平。对于卡灵顿事件风暴级别，对于与深部相邻的海岸线附近的电阻岩石区域，预计南北方向的地电场值为5.3±3.8 V / km，东西方向的地电场值为9.6±4.3 V / km高电导率的海洋和内陆，澳大利亚各地不同岩石类型的电导率之间存在很大的差异。此外，在这些区域中，地电场值可能会在50 km的网格间隔间隔内变化至少一个数量级。分析结果还表明，根据极端风暴Dst的比率，从观测到的风暴中得出的地电场时间序列网格按比例放大对观测到的风暴Dst进行评估是一种适用于澳大利亚地区的有效方法，该方法为不同的风暴形态提供了极端风暴情景。