Previous simulation efforts on geomagnetic disturbances (GMDs) and geomagnetically induced currents (GICs) mostly rely on global magnetohydrodynamics models, which explicitly calculate the magnetospheric currents and carry certain assumptions about the ionosphere currents. Therefore, the role of ionospheric and thermospheric processes to GMDs has not been fully evaluated. In this study, Global Ionosphere Thermosphere Model simulations for an idealized storm event have been conducted. Simply, the high-latitude electrodynamic forcing (potential pattern and particle precipitation) has been specified by empirical models. GMDs due to neutral-wind driven currents have been compared to those caused by magnetospheric convection driven currents during both the main and recovery phases. At locations where the high-latitude electric potential is dominant, neutral-wind driven currents are found to contribute to about 10%–30% of the total GMDs. During the recovery phase when the ion-convection pattern retreats to high latitudes, neutral-wind driven currents become the primary sources for GMDs at middle latitudes on the dayside due to the “flywheel” effect and the large dayside conductance. Our result strongly suggests that ionospheric and thermospheric processes should not be neglected when estimating GMDs and therefore GICs.

中文翻译：

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中性风驱动的电离层流引起的地磁扰动

先前对地磁扰动（GMD）和地磁感应电流（GIC）的模拟工作主要依赖于全局磁流体动力学模型，该模型明确计算磁层电流并对电离层电流进行某些假设。因此，电离层和热层过程对GMD的作用尚未得到充分评估。在这项研究中，对理想化风暴事件进行了全球电离层热层模型模拟。简而言之，高纬度电动力强迫（电势模式和粒子沉淀）已由经验模型指定。在主阶段和恢复阶段，中性风驱动电流引起的 GMD 与磁层对流驱动电流引起的 GMD 进行了比较。在高纬度电势占主导地位的地区，中性风驱动电流占总 GMD 的约 10%–30%。在离子对流模式退回到高纬度的恢复阶段，由于“飞轮”效应和大的日面电导，中性风驱动电流成为中纬度地区GMD的主要来源。我们的结果强烈表明，在估计 GMD 和 GIC 时不应忽视电离层和热层过程。