Faraday's law of induction is responsible for setting up a geoelectric field due to the variations in the geomagnetic field caused by ionospheric currents. This drives geomagnetically induced currents (GICs) which flow in large ground‐based technological infrastructure such as high‐voltage power lines. The geoelectric field is often a localized phenomenon exhibiting significant variations over spatial scales of only hundreds of kilometers. This is due to the complex spatiotemporal behavior of electrical currents flowing in the ionosphere and/or large gradients in the ground conductivity due to highly structured local geological properties. Over some regions, and during large storms, both of these effects become significant. In this study, we quantify the regional variability of dB/dt using closely placed IMAGE stations in northern Fennoscandia. The dependency between regional variability, solar wind conditions, and geomagnetic indices are also investigated. Finally, we assess the significance of spatial geomagnetic variations to modeling GICs across a transmission line. Key results from this study are as follows: (1) Regional geomagnetic disturbances are important in modeling GIC during strong storms; (2) dB/dt can vary by several times up to a factor of three compared to the spatial average; (3) dB/dt and its regional variation is coupled to the energy deposited into the magnetosphere; and (4) regional variability can be more accurately captured and predicted from a local index as opposed to a global one. These results demonstrate the need for denser magnetometer networks at high latitudes where transmission lines extending hundreds of kilometers are present.

中文翻译：

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dB / dt的区域变异性及其对GIC的意义

由于电离层电流引起的地磁场变化，法拉第感应定律负责建立地电场。这会驱动地磁感应电流（GIC），这些电流会流经大型地面技术基础设施，例如高压电力线。地电场通常是一种局部现象，在仅数百公里的空间尺度上表现出显着变化。这是由于电离层中电流流动的复杂时空行为和/或由于高度结构化的局部地质特性而导致的地面电导率大梯度。在某些地区以及大风暴期间，这两种影响都变得很明显。在这项研究中，我们量化了d B / d的区域变异性牛逼的芬诺斯堪的亚北部使用紧密放置的图像站。还研究了区域变化，太阳风条件和地磁指数之间的依赖性。最后，我们评估了空间地磁变化对跨越传输线的GIC建模的重要性。该研究的主要结果如下：（1）区域地磁干扰对于强风暴期间的GIC建模很重要；（2） d B / d t与空间平均值相比，可以相差几倍，最多可达三倍；（3） d B / d t其区域变化与沉积到磁层的能量耦合；（4）可以从局部指标而不是全局指标更准确地捕获和预测区域变化。这些结果表明，在存在延伸数百公里的传输线的高纬度地区，需要更密集的磁力计网络。