Space weather events can have wide ranging impacts on technological infrastructure; of particular concern is the potential for excess ground electric currents to cause damage to transformers in the UK high-voltage power grid. BGS produces models of the surface electric field derived from rapid geomagnetic variations as measured by the magnetic field instruments at our three UK observatories (Lerwick, Eskdalemuir and Hartland). These are used to provide an estimate of the real-time geomagnetically induced currents in the UK high-voltage electrical distribution network.

In 2012, the British Geological Survey initiated a project to make long-term direct measurements of the electric field at each of our three UK observatories, in order to understand and verify the computed surface electric field models. Previously, dedicated electric field measurements have not been routinely undertaken in the UK.

We present an update on the progress of this project and the validation of our electric field models, making comparisons between the computed electric field models and measured electric field data. A case study of the recent geomagnetic storm on 17th March 2015, where the electric field variation peaked at over 1000 mV/km at Lerwick, will be shown.