Space Weather Impacts on Ground Structures (SWIGS)

空间天气描述了近地空间不断变化的特性，这些特性影响了该区域，特别是电离层和磁层内的电流流动。太空天气是由太阳磁场活动引起的，在太阳黑子11年的周期内，太阳磁场活动因太阳外层大气中带电物质的喷发而消长。特别恶劣的太空天气会影响地面的导电基础设施，如电力传输系统（国家电网）、管道和铁路。地面网络处于危险之中，因为在空间天气的驱动下，空间中快速变化的电流会导致地面上的地磁场快速变化。这些磁场变化在地球上产生电场，在导电基础设施中充当“电池”。这种“电池”使地磁感应电流（GIC）通过导电网络流入或流出地球，而不是在更具电阻性的地面上。这些GIC扰乱了变压器的安全运行，有损坏和停电的风险。GIC还会导致长金属管网的腐蚀加剧，并干扰铁路信号系统。1989年3月，恶劣的太空天气损坏了英国的电力变压器，并导致加拿大魁北克省长时间停电。已知的最极端的太空天气事件——1859年的“卡灵顿事件”——造成了电报网络的大范围故障和不稳定，电报局发生火灾，低纬度地区出现极光现象。据估计，每十年发生另一次这种极端事件的可能性约为10%。因此，在英国政府的国家风险登记册中，恶劣的太空天气被认为是二十年一遇到二十年一遇的事件，因此行业和政府需要制定计划来降低风险。一些研究估计，在主要发达经济体中，由于长期停电，太空天气和GIC造成的经济后果每天可达数十亿美元。有一些数学模型可以说明太空天气是如何引起GIC的，以及它们可能出现在英国国家电网的哪个地方（没有英国管道或铁路网中GIC流动的模型）。然而，这些模型的功能非常有限，因此可能无法提供接地系统中GIC风险的真实情况，例如，突出显示某些位置存在风险，而实际上任何问题都存在于其他地方。为表示国家电网变电站的GIC而开发的电气模型忽略了一些关键特征，比如英格兰和威尔士的132kV输电系统模型，或者北爱尔兰的任何模型。英国地下的电导率只知道一部分，在一些地区根本不清楚。（我们需要知道电导率，以便计算充当GIC“电池”的电场。）英国政府投资公司的模型充其量只是“现在预测”，而且它们没有预测能力，尽管这是行业和政府的明确需求。我们还没有尝试和测试过现有的模型，甚至没有对地面磁场变化的预测模型。这是因为我们对电流如何在电离层和磁层中流动，它们如何相互联系以及它们与太阳风条件的关系的理解不充分。因此，在这个项目中，我们将升级现有的或创建新的模型，将电力、管道和铁路网中的GIC与电离层、磁层和太阳风条件联系起来。这些模型将解决我们在当前一代模型及其功能中发现的问题，并为行业和政府提供准确的数据，以评估我们的太空天气风险。在这些问题上取得进展的同时，我们还将从根本上提高我们对电流和电磁场在地球附近和地球内部相互作用方式的物理理解，以及它们如何影响我们所依赖的重要技术。

Space weather describes the changing properties of near-Earth space, which influences the flow of electrical currents in this region, particularly within the ionosphere and magnetosphere. Space weather results from solar magnetic activity, which waxes and wanes over the Sunspot cycle of 11 years, due to eruptions of electrically charged material from the Sun's outer atmosphere. Particularly severe space weather can affect ground-based, electrically conducting infrastructures such as power transmission systems (National Grid), pipelines and railways. Ground based networks are at risk because rapidly changing electrical currents in space, driven by space weather, cause rapid geomagnetic field changes on the ground. These magnetic changes give rise to electric fields in the Earth that act as a 'battery' across conducting infrastructures. This 'battery' causes geomagnetically induced currents (GIC) to flow to or from the Earth, through conducting networks, instead of in the more resistive ground. These GIC upset the safe operation of transformers, risking damage and blackouts. GIC also cause enhanced corrosion in long metal pipeline networks and interfere with railway signalling systems.Severe space weather in March 1989 damaged power transformers in the UK and caused a long blackout across Quebec, Canada. The most extreme space weather event known - the 'Carrington Event' of 1859 - caused widespread failures and instabilities in telegraph networks, fires in telegraph offices and auroral displays to low latitudes. The likelihood of another such extreme event is estimated to be around 10% per decade. Severe space weather is therefore recognised in the UK government's National Risk Register as a one-in-two to one-in-twenty year event, for which industry and government needs to plan to mitigate the risk. Some studies have estimated the economic consequence of space weather and GIC to run to billions of dollars per day in the major advanced economies, through the prolonged loss of electrical power.There are mathematical models of how GIC are caused by space weather and where in the UK National Grid they may appear (there are no models of GIC flow in UK pipelines or railway networks). However these models are quite limited in what they can do and may therefore not provide a true picture of GIC risk in grounded systems, for example highlighting some locations as being at risk, when in fact any problems lie elsewhere. The electrical model that has been developed to represent GIC at transformer substations in the National Grid misses key features, such as a model of the 132kV transmission system of England and Wales, or any model for Northern Ireland. The conductivity of the subsurface of the UK is known only partly and in some areas not at all well. (We need to know the conductivity in order to compute the electric field that acts as the 'battery' for GIC.) The UK GIC models only 'now-cast', at best, and they have no forecast capability, even though this is a stated need of industry and government. We do not have tried and tested now-cast models, or even forecast models, of magnetic variations on the ground. This is because of our under-developed understanding of how currents flow in the ionosphere and magnetosphere, how these interconnect and how they relate to conditions in the solar wind. In this project we will therefore upgrade existing or create new models that relate GIC in power, pipe and railway networks to ionospheric, magnetospheric and solar wind conditions. These models will address the issues we have identified with the current generation of models and their capabilities and provide accurate data for industry and governments to assess our risk from space weather. In making progress on these issues we will also radically improve on our physical understanding of the way electrical currents and electromagnetic fields interact near and in the Earth and how they affect the important technologies we rely on.