Sensitivity of geomagnetically induced currents to varying auroral electrojet and conductivity models
Sensitivity of geomagnetically induced currents to varying auroral electrojet and conductivity models
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DOI：
10.1186/s40623-014-0168-9
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发表时间：
2015-02-15
影响因子：
3
通讯作者：
Beggan, Ciaran D.
中科院分区：
文献类型：
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作者：
Beggan, Ciaran D.
地磁感应电流(GIC)是由磁场大小的快速变化与地球表面的导电相互作用而产生的。不断变化的磁场会产生电流，在陆地和海洋等导电结构截然不同的区域之间的边界上，电流尤其强烈。一种被称为“薄片近似”的技术可用于确定地球表面的电场，进而允许计算电网内高压节点的接地连接中的GIC。薄片近似使用2D表面上感兴趣区域上的空间变化的电导，结合上岩石圈电导的一维分层模型。我们在英国上空的不同地点制作了极光电喷流的合成模型，并研究了不同的2D薄板模型的影响。我们评估了不同的二维表面电导模型，并改变了潜在的一维电导模型来模拟导电岩石圈的电阻效应。利用一个先进的高压配电网网络模型，在给定各种合成电射流和电导率模型的输入表面电场的情况下，计算了系统中每个节点的期望GIC。我们发现，电喷流位置是控制GIC尺寸的主要因素，电导率一般是二阶效应，尽管它可能是局部重要的。
Geomagnetically induced currents (GIC) are created by the interaction of rapid changes in the magnitude of the magnetic field with the conductive subsurface of the Earth. The changing magnetic field induces electric currents, which are particularly strong along boundaries between regions of contrasting conductivity structure such as the land and sea. A technique known as the 'thin-sheet approximation' can be used to determine the electric field at the Earth's surface, which in turn allows the calculation of GIC in the earthing connections of high-voltage nodes within a power grid. The thin-sheet approximation uses a spatially varying conductance over the region of interest on a 2D surface, combined with a 1D layered model of upper lithosphere conductance. We produce synthetic models of the auroral electrojet in different locations over the United Kingdom (UK) and investigate the effects of varying the 2D thin-sheet model. We assess different two-dimensional surface conductance models and vary the underlying 1D conductivity models to simulate the effects of resistant through to conductive lithosphere. With an advanced network model of high-voltage electrical distribution grid, we compute the expected GIC at each node in the system given the input surface electric fields from the various synthetic electrojets and conductivity models. We find that the electrojet location is the primary control on the size of GIC, with conductivity being a second-order effect in general, though it can be locally important.