Space Weather Impacts on Ground Structures (SWIGS)

空间天气描述了近地空间性质的变化，这影响了这一区域的电流流动，特别是在电离层和磁层内。空间天气是太阳磁场活动的结果，太阳磁场活动在太阳黑子11年的周期中起伏不定，这是由于太阳外层大气中的带电物质喷发造成的。尤其是恶劣的空间天气会影响地面的电力传导基础设施，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，太空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了电场，在整个传导基础设施中起到了‘电池’的作用。这种“电池”导致地磁感应电流(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还会导致金属长管道网络的腐蚀加剧，并干扰铁路信号系统。1989年3月的严重太空天气损坏了英国的电力变压器，并导致加拿大魁北克地区长时间停电。已知的最极端的太空天气事件--1859年的卡林顿事件--导致电报网络广泛故障和不稳定，电报办公室起火，低纬地区出现极光显示。据估计，再发生一次这样的极端事件的可能性约为每十年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一种二分之一到二十年一遇的事件，行业和政府需要计划减轻这种风险。一些研究估计，空间天气和GIC的经济后果在主要发达经济体通过长时间的电力损失每天高达数十亿美元。空间天气如何引起GIC以及它们可能出现在英国国家电网中的位置有数学模型(英国管道或铁路网中没有GIC流动模型)。然而，这些模型的能力相当有限，因此可能无法提供接地系统中GIC风险的真实图景，例如，突出某些位置处于风险中，而实际上任何问题都存在于其他位置。为代表国家电网中变电站的GIC而开发的电气模型缺少关键特征，例如英格兰和威尔士的132千伏输电系统的模型，或北爱尔兰的任何模型。人们对英国地下的导电性只有部分了解，在某些地区则完全不清楚。(我们需要知道电导率，以便计算充当GIC电池的电场。)英国的GIC模型充其量只是“现在预测”，而且他们没有预测能力，尽管这是行业和政府的明确需求。我们还没有尝试和测试地面上的磁场变化的现在预测模型，甚至预测模型。这是因为我们对电离层和磁层中的电流如何流动，这些电流如何相互连接，以及它们与太阳风条件的关系的了解还不够深入。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对当前一代模型及其能力所发现的问题，并为业界和政府评估我们的空间天气风险提供准确的数据。为了在这些问题上取得进展，我们还将从根本上改善我们对电流和电磁场在地球附近和内部相互作用的方式以及它们如何影响我们所依赖的重要技术的物理理解。

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.