Geomagnetism Builds a Space Weather Forecasting Capability / / by Alan Thomson

Alan Thomson is Head of Geomagnetism at BGS. He specialises in geomagnetic hazards to ground-based infrastructure (such as power transmission and pipeline networks), caused by space weather. Alan has also carried out research into global geomagnetic field models to understand better the various sources of the Earth’s magnetic field. Vice-president of the International Association for Geomagnetism and Aeronomy and Chair of the Executive Council of INTERMAGNET, Alan currently leads two NERC-funded consortia on space weather hazard to technology (SWIGS and SAGE.) Here, he tells us about the government's new investment in space weather forecasting... 

The Northern Lights (Aurora Borealis), which is caused by geomagnetic storms

Geomagnetic storms and the Northern Lights have been known about for centuries, even if the science behind them wasn’t understood, for instance, that the Sun’s magnetism was the culprit. Another thing that wasn’t clear until the 1850s, was that geomagnetic storms have an impact on technologies that society relies on. Back in the 1850s, this was just the telegraph, sometimes referred to as the ‘Victorian Internet’. Nowadays, a wide spectrum of things that we rely on can be affected by the more general phenomenon ‘space weather’, of which geomagnetic storms are a part. These include the National Grid, satellite communications, radio, TV, and applications relying on precise satellite global positioning, like GPS. 
Plans for magnetometer sites (green) and existing installations (blue)

The Geomagnetism Capability, over several decades, has developed increasingly sophisticated models of space weather impact on power grids and metal pipeline networks. In this time, we have provided real-time data products and services for National Grid, EDF Energy, Scottish Power, ESA, the Met Office and others. We have also influenced government policy and planning in this area through membership of the BEIS-sponsored ‘Space Environment Impact Expert Group’. 

Space weather has sat for a decade on the government’s National Risk Register, as a 'once in two to 20-year risk of severe space weather with moderate impact'. It actually ranks just two steps lower on the scale, in terms of potential impact on our society, than an influenza pandemic. Understandably - even more so following recent events - this means the government takes it seriously!

Earlier this year, the Geomagnetism Capability bid for, and won, funding for a landmark project to develop space weather services in the area of ‘ground effects’. The UKRI Strategic Priorities Fund has invested £20M in a range of projects for academic institutes to provide the Met Office (and by extension the government), with data, products and tools to forecast space weather and its impact on the various technologies that the country relies on. This is an ambitious and certainly world-leading programme, whose influence beyond these shores is likely to be significant over time.

The National Environment Research Council (NERC) and Science and Technologies Facilities Council (STFC) came together to propose eleven projects on all aspects of space weather, from the Sun to the Earth. The programme is collectively known as ‘Space Weather Instrumentation, Measurement, Modelling and Risk’, or SWIMMR, and our project is known as SAGE, or ‘SWIMMR Activities in Ground Effects’. 

Surface electric field model during severe space weather (2013)

SAGE will run until 2023 and I will lead a small, focussed group of scientists from BGS, the British Antarctic Survey, Imperial College and the Mullard Space Science Laboratory (University College London). SAGE follows on from our leadership of SWIGS (Space Weather Impacts on Ground-based Systems), a NERC ‘Highlight Topic’. Beginning in 2017 and running to 2021, SWIGS comprised of nine UK universities and institutes and more than twenty researchers. Whereas SAGE is a directed research programme and concentrates on delivering an operational system for space weather forecasts, SWIGS was (and still is) about the underpinning blue-sky science. 

But what are ‘ground effects’ and why is BGS uniquely placed to lead SAGE?

‘Ground effects’ refers to the impact from space weather on large-scale technologies that are electrically grounded in the Earth. This therefore includes the power grid, the high-pressure gas transmission pipeline network and potentially the UK rail network. Geomagnetic storms are associated with electrical currents that flow in the ionosphere, at above 80-90 km. These currents are enhanced during significant space weather, growing and diminishing over seconds to minutes. These time scales are quite similar to the light flickering you see when watching the Northern Lights, as these are also caused by changing currents refreshed from space and driven by solar magnetism.

Faraday’s Law of electromagnetism tells us that such changing electrical currents will induce a changing magnetic field in a conducting body, which is exactly what the Earth is. In turn, because of magneto-telluric (MT) principles, this changing magnetic field produces a surface electric field on the conductor. Slightly simplifying the physics, this electric (or telluric) field then acts somewhat like a battery between the Earthing points in any large network. Emphasis on ‘large’ is important here: the electric field is normally much less than one Volt per kilometre, so the voltage needs to scale up over many kilometres. During the most severe space weather, we might measure 1-10 Volts/km in the UK. This battery causes currents to flow in the network that can trigger, for example, power transformers to mis-operate, or metal pipelines to corrode over time. 

BGS UK Earth electrical conductivity model (pink is more conductive, blue is less conductive) 

The Geomagnetism Capability and BGS is therefore the natural home of this science and these applications. We have unique UK understanding and skills in geomagnetic storms and real-time data and we understand the geophysics. This was what was rewarded when we won the SAGE grant.
What is really novel about SAGE is the emphasis on forecasting. This has never been possible before, whether in the UK or elsewhere. The reason we can do this now is that Imperial and BAS have new models that describe how the magnetic changes on the ground are driven by conditions in near-Earth space. There are spacecraft out there that continuously measure solar wind conditions and because of the propagation lags through the Sun-Earth system, we can develop forecasting of effects on the ground up to one hour ahead, based on the spacecraft measurements. Our forecasts will therefore be based on what is happening right now, but a million miles or more upstream towards the Sun; a new frontier for BGS science! SAGE will also bring Machine Learning to some tricky forecasting issues and Mullard Space Science Laboratory will lead this, with some input from us.

BGS will undertake a countrywide magnetotellurics (MT) survey to improve our sub-surface conductivity model. Scotland was surveyed during SWIGS; now it is England and Wales’ turn. This will allow us to more accurately ‘nowcast’ and forecast telluric fields across Great Britain based on magnetic measurements and MT principles, and now/forecast the damaging currents that might flow in the grounded networks. It will also, in a neat pure science offshoot, provide major new datasets for solid Earth geophysics research. Juliane Hübert is our MT expert and will coordinate our fieldwork and we will employ a couple of fieldworkers for the project’s duration. We also plan to deploy simpler magnetometer systems at Herstmonceux (thanks for your support), Fermanagh (thanks GSNI), and possibly Keyworth (watch this space). This would give us an unprecedented monitoring of magnetic storms during the life of SAGE. 
BGS power grid network model

Ciaran Beggan and Gemma Richardson will lead developments in power grid and pipeline network modelling. We will collectively work on developing a warning system for the UK rail network. Real-time data from the UK magnetic observing network is essential to make our forecasting system work. Ellen Clarke will therefore coordinate our activities in this area. Our model development and data visualisation will also likely tap into skills in the Informatics area. 

As lead PI, I am really excited about SAGE. For me, it promises to be the culmination of years of investment in Geomagnetism science, measurements and IT. It will take space weather forecasting, rudimentary to date, and place it alongside the physics-based discipline that is modern meteorology and numerical weather forecasting. However, don't expect me to be presenting our space weather forecast at the end of the BBC News every night. That can be someone else’s aspiration!

For more information please visit the BGS Geomagnetism site