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Solar Storm Moves Earth’s Magnetic Field, Increases Current in Power Grid
The aurora borealis lighting up the sky green for Saint Patrick’s Day (17 March) 2015. This image was taken from Co. Mayo and shows the display above a sea stack known as Dún Briste. According to one legend, a pagan chieftain named Crom Dubh lived there. He refused to listen to Saint Patrick who tried to convert him to Christianity. St. Patrick hit the ground with his crozier and the stack was separated from the mainland, leaving Crom Dubh to die there.
Credit: (c) Brian Wilson
The resulting geomagnetic storms – the strongest for a decade – led to dramatic displays of the northern lights and induced significant additional currents in the power grids of Britain and Ireland. Despite that, neither grid suffered any damage, boosting the prospects for resilience when worse ‘space weather’ events take place.
Two research groups, led by Peter Gallagher of Trinity College Dublin and Gemma Kelly of the British Geological Survey (BGS), will this week (7 and 8 July) give presentations on the effects of the storm this week at the National Astronomy Meeting atVenue Cymru in Llandudno, Wales.
As far back as 1852, Dublin-born Sir Edward Sabine showed that magnetic storms waxed and waned with the number of spots on the Sun. Not long after this, in 1859, Richard Carrington observed a huge solar flare that was followed within a day by brilliant displays of the northern lights in regions as far south as Italy and Cuba.
Map of the modelled changes in electric field caused by the St Patrick’s Day storm, where blue is low and red is high. Large geomagnetic storms can cause unwanted currents to flow through electrical power grids. On this occasion though, no damaging effects were seen in the Irish or British power grid.
Nowadays, society has become vastly more dependent on technological systems for communications and electricity. These too can be disturbed by magnetic storms – navigation systems can have positioning errors, radio transmission can be blacked out, and power grids can become unstable. The most infamous impact occurred in 1989 in Canada, when a magnetic storm interrupted electrical power for more than six million people for nine hours at a cost of over C$13 billion (£6.6 billion, 9.3 billion Euros).
For this reason scientists at Trinity College Dublin and at the British Geological Survey were on high alert this Saint Patrick’s Day. “A warning message from our magnetometer network developed by Trinity and the Dublin Institute for Advanced Studies notified me of the onset of a large geomagnetic storm as I watched the Saint Patrick’s Day parade with my family”, according to Professor Peter Gallagher, head of solar physics and space weather at Trinity. “That evening, the sky danced red, pink and notably green across Ireland and the UK.”
A graph showing how compass direction changed during the 17 March geomagnetic storm, measured at three observing stations across the UK. The storm was powerful enough to shift the apparent direction of magnetic north by several degrees.
Dr Kelly added: “This storm and a more recent one in June were the biggest we have seen in over 10 years. They produced the biggest electrical fields on the ground – and hence currents – we have seen since our system started operation in 2012. Fortunately, the British power grid held up well too, so it gives us more confidence that at least some of our systems are pretty resilient to inclement space weather.”
The Saint Patrick’s Day storm has enabled the Trinity team to demonstrate that their alert system works in Ireland and helped BGS scientists gather data on how the storms affected Britain. Blake concludes, “We can now monitor and model magnetic storms in near-real time, which not only allows us to understand the physics of such phenomena, but also to provide a valuable service for power operators.”
Dr Robert Massey
Royal Astronomical Society
Professor Peter Gallagher
School of Physics
Trinity College Dublin
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