Space Weather Impacts on Ground-based Systems (SWIGS)

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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.