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Geomagnetic Conditions in Ireland During the St. Patrick's Day 2015 Storm

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posted on 06.07.2015 by Sean Blake, Peter Gallagher, Joseph McCauley, Alan Jones, Colin Hogg, Ciaran Beggan, Alan Thomson, Gemma Kelly, David Bell

Poster at UK National Astronomy Meeting in Llandudno, Wales on July 5-9, 2015 (


Two coronal mass ejections were launched in quick succession from the Sun on March 15, 2015. They impacted the Earth's magnetosphere two days later on St. Patrick's Day (March 17), resulting in a geomagnetic storm with a planetary K-Index of 8.

Magnetic variations were measured across a recently deployed magnetometer network in Ireland and geoelectric fields were measured at a site in Co. Leitrim (magnetic latitude 57.08°). A local K-index maximum of 7 was calculated at Birr, Co. Offaly (magnetic latitude 55.97), while the aurora

borealis accompanying the geomagnetic storm was visible as far south as Co. Waterford (magnetic latitude 55.13°).

The British Geological Survey thin-sheet surface electric field model was used together with our magnetometer measurements to calculate electric fields and geomagnetically induced currents (GICs) in the Irish power grid.

Although it was one of the most magnetically disturbed days in a decade, with dB/dt reaching ~50 nT/min, the peak GIC level estimated in the Irish power grid was ~10 Amps. Note, no adverse effects were reported in the Irish power grid demonstrating its resilience to geomagnetic storms of this magnitude.