Geomagnetically Induced Currents and Space Weather: Pi3 Pulsations and Extreme Values of Time Derivatives of the Geomagnetic Field’s Horizontal Components
Geomagnetically Induced Currents and Space Weather: Pi3 Pulsations and Extreme Values of Time Derivatives of the Geomagnetic Field’s Horizontal Components
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地磁感应电流和空间天气：地磁场水平分量的 Pi3 脉动和时间导数的极值
DOI：
10.1134/s1069351318050130
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Yury P. Gusev
中科院分区：
文献类型：
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作者：
N. Yagova;V. Pilipenko;E. Fedorov;A. D. Lhamdondog;Yury P. Gusev
估计地磁场水平分量的时间导数和预测超过给定阈值水平的扰动（超阈值扰动）发生的概率的问题出现在与地磁感应电流（gic）有关的应用中。在本研究中，我们考虑了准周期为102 ~ 103 s的Pi3脉动的时空结构，在此期间，IMAGE网络的极光站和亚极光站记录了经向（沿纵圈）BX分量和纬向（沿纬圈）BY分量的导数超过阈值。|dBX/dt|极值主要出现在具有复频率含量的Pi3脉动背景下，而|dBY/dt|极值则出现在伴随亚暴演化的湾状扰动的形成（衰减）阶段与脉动场的相应阶段相吻合时。利用叠代年代分析技术，研究了亚极光纬度的导数|dBX/dt|和|dBY/dt|达到超阈值的条件。在行星际磁场垂直分量为负的情况下，导数的极值最常出现在中度磁暴的主阶段或风暴之后的高次风暴活动期间。在Pi3脉冲的高振幅处，出现超过阈值的概率增加，这取决于它们的频谱含量。超阈值扰动|dBY/dt|的分析和预报问题比较复杂，因为扰动的尺度沿纬度方向小，沿子午线方向大。这可能导致南北方向电力线在经度窄带范围内的地磁扰动产生GIC激励，在测量过程中可能会遗漏。
The problem of estimating the time derivatives of the horizontal components of the geomagnetic field and forecasting the probability of the occurrence of perturbations that exceed a given threshold level (the over-threshold perturbations) arises in the applications concerned with the geomagnetically induced currents (GICs). In this work, we consider the temporal and spatial structure of the Pi3 pulsations with quasi-periods of 102 to 103 s during which the auroral and subauroral stations of the IMAGE network record over-threshold values in the derivatives of the meridional (along the longitudinal circle) BX component and latitudinal (along the latitudinal circle) BY component. The extreme |dBX/dt| values mainly develop against the background of the Pi3 pulsations with a complex frequency content, whereas the extreme |dBY/dt| values appear when the buildup (decay) phases of the bay-like disturbance associated with the evolution of a substorm coincide with the respective phases of the field of pulsations. The conditions under which the derivatives |dBX/dt| and |dBY/dt| reach their over-threshold values are studied for subauroral latitudes by the technique of superposed epoch analysis. The extreme values of the derivatives most frequently occur during the main phase of moderate magnetic storms or beyond the storm—during high substorm activity under the conditions of a negative vertical component of the interplanetary magnetic field. The probability of the occurrence of over-threshold values increases at high amplitudes of the Pi3 pulsations and depends on their spectral content. The problem of analyzing and forecasting the over-threshold |dBY/dt| perturbations is complicated by the fact that the scale of the perturbations is small along the lines of latitude and large along the meridians. This can result in GIC excitation in the North–South oriented electric power lines by the geomagnetic perturbations localized within a narrow band in longitude which can be missed during the measurements.