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Geomagnetically Induced Currents at Middle Latitudes: 1. Quiet-Time Variability
Space Weather ( IF 4.288 ) Pub Date : 2021-08-19 , DOI: 10.1029/2021sw002729
A. C. Kellerman 1 , Ryan Mcgranaghan 2 , Jacob Bortnik 3 , Brett A. Carter 4 , Joseph Hughes 2 , Robert F. Arritt 5 , Karthik Venkataramani 2 , Charles H. Perry 5 , Jackson McCormick 6 , Chigomezyo M. Ngwira 2 , Morris Cohen 6 , Jia Yue 7, 8
Affiliation  

Geomagnetically induced currents (GICs) at middle latitudes have received increased attention after reported power grid disruptions due to geomagnetic disturbances. However, quantifying the risk to the electric power grid at middle latitudes is difficult without understanding how the GIC sensors respond to geomagnetic activity on a daily basis. Therefore, in this study the question “Do measured GICs have distinguishable and quantifiable long-period and short-period characteristics?” is addressed. The study focuses on the long-term variability of measured GIC, and establishes the extent to which the variability relates to quiet-time geomagnetic activity. GIC quiet-day curves (QDCs) are computed from measured data for each GIC node, covering all four seasons, and then compared with the seasonal variability of thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM)-simulated neutral wind and height-integrated current density. The results show strong evidence that the middle-latitude nodes routinely respond to the tidal-driven Sq variation, with a local time and seasonal dependence on the direction of the ionospheric currents, which is specific to each node. The strong dependence of GICs on the Sq currents demonstrates that the GIC QDCs may be employed as a robust baseline from which to quantify the significance of GICs during geomagnetically active times and to isolate those variations to study independently. The QDC-based significance score computed in this study provides power utilities with a node-specific measure of the geomagnetic significance of a given GIC observation. Finally, this study shows that the power grid acts as a giant sensor that may detect ionospheric current systems.

中文翻译:

中纬度地磁感应电流:1. 静时变率

中纬度地区的地磁感应电流 (GIC) 在报告因地磁扰动导致电网中断后受到越来越多的关注。然而,如果不了解 GIC 传感器每天如何响应地磁活动,就很难量化中纬度地区电网的风险。因此,在本研究中,“测量的 GIC 是否具有可区分和可量化的长周期和短周期特征?”的问题。被解决。该研究侧重于测量的 GIC 的长期变异性,并确定了变异性与安静时间地磁活动相关的程度。GIC 静日曲线 (QDC) 是根据每个 GIC 节点的测量数据计算得出的,涵盖所有四个季节,然后与热层-电离层-电动力学大环流模型(TIE-GCM)-模拟中性风和高度积分电流密度的季节变化进行比较。结果表明,中纬度节点通常会对潮汐驱动的 Sq 变化做出反应,本地时间和季节依赖于电离层电流的方向,这是每个节点特有的。GIC 对 Sq 电流的强烈依赖性表明,GIC QDC 可用作稳健的基线,用于量化 GIC 在地磁活动期间的重要性并隔离这些变化以独立研究。本研究中计算的基于 QDC 的显着性得分为电力公司提供了特定节点测量给定 GIC 观测的地磁显着性。
更新日期:2021-08-19
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