Filling the gaps
Filling the gaps
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DOI：
10.1093/astrogeo/atac080
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发表时间：
2022
影响因子：
0.8
通讯作者：
Beggan C
中科院分区：
文献类型：
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作者：
Beggan C
英国.但是，相关的地面磁场变化也对电力、铁路和管道系统产生潜在的危险影响（Kelly等人，2017）。当极光椭圆在英国上空向南移动时，地面上的磁场迅速变化。但是，这个椭圆的赤道边界，而不是有一个整洁的直边，有波动，摆动和弯曲的几百公里的波长。这些可能会导致磁场沿前沿沿着增强，特别是在英国纬度（Freeman等人，2019）。英国有三个历史悠久的科学地磁观测站，分别位于勒威克（设得兰群岛）、埃斯克达拉缪尔（邓弗里斯和加洛韦）和哈特兰（德文郡）。它们形成一条大致南北走向的线，但经度变化不大。因此，我们无法感知这条线之外的磁场，并且错过了关于波浪状极光椭圆形边缘磁场局部变化的重要信息。作为国家环境研究中心资助的空间气象仪器、测量、建模和风险地面效应活动项目的一部分，英国地质调查局地磁小组在北方爱尔兰、莱斯特郡和苏塞克斯安装了三个新的变差仪站，以扩大东西方向的覆盖范围。这些系统包括一个三轴矢量磁通门磁力仪、一台数字化仪/记录仪计算机和一个用于传输近实时数据的4G调制解调器。该系统使用电池和太阳能电池板进行独立供电。电子设备和电池装在一个防水容器里，放在一个重新利用的花园棚子里。磁力计埋在地下1米左右的桶中，以减少每日温度变化的影响，距离电子设备和太阳能电池板约6米，以减少电磁噪声。传感器在Eskdalemuir天文台进行了校准，以通过与科学仪器的同步测量进行比较来确定缩放和偏移因子。然而，由于温度不保持恒定，校准因子也不每周检查一次（在天文台），磁变仪的磁场值被认为是相对的，而不是绝对的。它们可以很好地捕捉到磁场的短期变化，大约在几个小时的量级，这对空间天气应用很有用，但是这些测量结果不能用于确定地球核心磁场的衰减角或长期变化。两个系统安装在农村地区的领域，在佛罗伦萨法院（FLO）国家信托基金，弗马纳和附近的市场哈伯勒，莱斯特郡（LEI）。第三个位于埃尔斯特蒙塞（HTX）的英国地质调查局空间大地测量设施，与主电源和通信连接。这三个新的变感仪填补了英国地质调查局和其他Intermagnet天文台之间的空白，将站点间距离缩短到400公里以下，从而提高了整体覆盖范围。英国的六个磁力站将允许创建非常详细的磁场实时地图，结合地面电阻率，我们可以每五分钟计算一次感应地电场。大的地电场可以流经高压变压器等超导体，产生地磁感应电流（Huebert等人，2020年）。这种电流使变压器偏离其最佳工作状态，导致温度波动和50 Hz工作频率的谐波失真。如果这些变得足够大，则Transformer安全系统将启动以阻止进一步的损坏（Boteler 2019）。实时监控将有助于识别危险情况。那个...
UK. But the associated ground magnetic field variation also has potentially hazardous effects on power, rail, and pipeline systems (Kelly et al. 2017). As the auroral oval moves southwards over the UK, the magnetic field on the ground changes rapidly. But the equatorward boundary of that oval, rather than having a neat straight edge, has fluctuations, wiggles and bends on the order of a few hundred kilometres in wavelength. These can cause stronger-than-expected enhancements of the field along the leading edge, particularly at UK latitudes (Freeman et al. 2019). The UK has three long-established scientific geomagnetic observatories, in Lerwick (Shetland), Eskdalemuir (Dumfries and Galloway) and Hartland (Devon). These form an approximately north-south line but have little variation in longitude. Thus, we are unable to sense the magnetic field off this line and are missing vital information about local variations in the field from the wavy auroral oval edge. As part of the NERC-funded Space Weather Instrumentation, Measurement, Modelling and Risk (SWIMMR) Activities in Ground Effects (SAGE) project, the British Geological Survey geomagnetism team have installed three new variometer stations, in Northern Ireland, Leicestershire and Sussex, in order to expand the coverage in the east-west directions. These systems consist of a three-axis vector fluxgate magnetometer, a digitizer/logger computer and a 4G modem to transmit near-real-time data. The systems use batteries and a solar panel for independent power supply. The electronics and batteries are housed in a waterproof container within a repurposed garden shed. The magnetometer is buried in a barrel around 1 m below ground level, to reduce the effect of daily temperature changes, and around 6 m from the electronics and solar panels to reduce electromagnetic noise. The sensors were calibrated at the Eskdalemuir observatory to determine scaling and offset factors by comparison to simultaneous measurements from the science instruments. However, as the temperature is not kept constant and the calibration factors are not checked weekly (as they are at observatories), the magnetic field values from variometers are considered to be relative rather than absolute. They capture the short-term change of the magnetic field well on the order of hours–useful for space weather applications–but the measurements cannot be used for determining the angle of declination or long-term changes of the Earth’s core field. Two systems were installed in fields in rural areas, at Florence Court (FLO) National Trust, Fermanagh and near Market Harborough, Leicestershire (LEI). The third is located at the BGS Space Geodesy Facility in Herstmonceux (HTX) and is connected to mains power and communications. The three new variometers fill in the gaps between the BGS and other Intermagnet observatories, reducing the inter-site distance to less than 400 km thus improving the overall coverage. The six UK magnetic stations will allow very detailed real-time maps of the magnetic field to be created and, in combination with the ground resistivity, we can compute the induced geoelectric field every five minutes. Large geoelectric fields can flow through earthed conductors such as high-voltage transformers creating geomagnetically induced currents (Huebert et al. 2020). Such currents push transformers out of their optimal operating regime, causing temperature fluctuations and harmonic distortion on the 50 Hz operation frequency. If these become large enough the transformer safety systems engage to stop further damage (Boteler 2019). Real-time monitoring will help identify when conditions are hazardous. The …