The intensification of the fluctuating geomagnetic field during space weather events leads to generation of a strong electric field in the conducting earth, which drives geomagnetically induced currents (GICs) in grounded technological systems. GICs can severely affect the functioning of such infrastructure. The ability to realistically model the ground electric field (GEF) is important for understanding the space weather impact on technological systems. We present the results of three‐dimensional (3‐D) modeling of the GEF for the eastern United States during a geomagnetic storm of March 2015. The external source responsible for the storm is constructed using a 3‐D magnetohydrodynamic (MHD) simulation of near‐Earth space. We explore effects from conductivity contrasts for various conductivity models of the region, including a 3‐D model obtained from inversion of EarthScope magnetotelluric data. As expected, the GEF in the region is subject to a strong coastal effect. Remarkably, effects from landmass conductivity inhomogeneities are comparable to the coastal effect. These inhomogeneities significantly affect the integrated GEF. This result is of special importance since the computation of GICs relies on integrals of the GEF (voltages), but not on the GEF itself. Finally, we compare the GEF induced by a laterally varying (MHD) source with that calculated using the plane wave approximation and show that the difference is perceptible even in the regions that are commonly considered to be negligibly affected by lateral nonuniformity of the source. Overall, the difference increases toward the north of the model where effects from laterally variable high‐latitude external currents become substantial.

中文翻译：

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探索横向电导率对比对美国东部地面电场风暴时间行为的影响

在太空天气事件期间，不断变化的地磁场会导致在导电地球中产生强电场，从而在接地的技术系统中驱动地磁感应电流（GIC）。GIC会严重影响此类基础架构的功能。现实地模拟地面电场（GEF）的能力对于理解太空天气对技术系统的影响非常重要。我们介绍了2015年3月的一次地磁风暴期间美国东部地区GEF的三维（3D）建模结果。使用3D磁流体动力学（MHD）模拟构造了负责该风暴的外部源近地空间。我们探索了该区域各种电导率模型的电导率对比的影响，包括从EarthScope大地电磁数据反演获得的3D模型。不出所料，该区域的全环基金受到强烈的沿海影响。值得注意的是，陆地电导率不均匀性所产生的影响与沿海地区的影响相当。这些不均匀性严重影响了整合的GEF。由于GIC的计算依赖于GEF（电压）的积分，而不依赖于GEF本身，因此该结果特别重要。最后，我们将横向变化（MHD）源诱发的GEF与使用平面波近似计算得出的GEF进行了比较，结果表明，即使在通常被认为受到源横向不均匀性影响的区域中，该差异也是可以感知的。总体，