利用大地电磁传递函数对爱尔兰地电场进行近场预报
Nowcasting Geoelectric Fields in Ireland using Magnetotelluric Transfer Functions
摘要：
由地电场驱动的地磁感应电流（GIC）对地面基础设施（如电网和管道）构成危害。在这里，提出了一种新的方法，模拟地电场在近实时，提供有价值的信息，以帮助减轻GIC的影响的目的。该方法使用来自爱尔兰磁强计网络（MagIE; \url{www.magie.ie}）的磁场测量值，使用球形基本电流系统（SECS）对磁强计之间的地磁场变化进行插值，并使用高密度（$<~40~km$）大地电磁传递函数（MT-TF）网络（包括岛屿）估计局部电场。该模型进行了优化，以接近实时的工作，校正曲线应用于地电场时间序列。在四个地点测量的若干地磁风暴的电场成功地验证了这种方法，提供了精确的电场，从实时延迟高达1分钟，具有高度的一致性（$0.70 - 0.85$）和信噪比（信噪比; $3.2 - 6.5$）相对于测量的电场验证时间序列。（相干性$~=~0.80 - 0.89$和SNR $~=~4.0 - 7.0$）。还简要评估了电流畸变对模型的影响，电流畸变校正导致在区域尺度上更均匀地表示电场的方向。
英文摘要：
Geomagnetically induced currents (GIC) driven by geoelectric fields pose a hazard to ground-based infrastructure, such as power grids and pipelines. Here, a new method is presented for modelling geoelectric fields in near real time, with the aim of providing valuable information to help mitigate the impact of GIC. The method uses magnetic field measurements from the Magnetometer Network of Ireland (MagIE; \url{www.magie.ie}), interpolates the geomagnetic field variations between magnetometers using spherical elementary current systems (SECS), and estimates the local electric field using a high density ($<~40~km$) network of magnetotelluric transfer functions (MT-TF) encompassing the island. The model was optimised to work in near real time, with a correction curve applied to the geoelectric field time series. This approach was successfully validated with measured electric fields at four sites for a number of geomagnetic storms, providing accurate electric fields up to a 1-minute delay from real time, with high coherence ($0.70 - 0.85$) and signal-to-noise ratio (SNR; $3.2 - 6.5$) relative to measured electric field validation time series .This was comparable to a standard non real-time geoelectric field model (coherence$~=~0.80 - 0.89$ and SNR$~=~4.0 - 7.0$). The impact of galvanic distortion on the model was also briefly evaluated, with a galvanic distortion correction leading to a more homogeneous representation of the direction of the electric field, at a regional scale.
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