Regional geomagnetic disturbances in Fennoscandia: statistical observations, modelling, and driving mechanisms

Andrew Dimmock - Swedish Institute of Space Physics; Lisa Rosenqvist - Swedish Research Defence Agency, Sweden; Daniel Welling - (University of Texas at Arlington, United States; Ari Viljanen - Finnish Meteorological Institute, Finland; Colin Forsyth - UCL Mullard Space Science Laboratory, United Kingdom; Mervyn Freeman - British Antarctic Survey, United Kingdom; Jonathan Rae - Northumobria University, United Kingdom; Ilja Honkonen - Finnish Meteorological Institute, Finland; Richard Boynton - University of Sheffield, United Kingdom; Michael Balikhin - University of Sheffield, United Kingdom; Elizabeth Elizabeth - University of Texas at Arlington, United States; Emiliya Yordanova - Swedish Intitute of Space Physics Uppsala, Sweden

Session: Ground-Level Geomagnetically Induced Currents

Abstract

Geomagnetically Induced Currents (GICs) pose risks to ground-based infrastructures such as power lines and pipelines. Dynamic spatiotemporal behaviour of geospace currents causes rapid geomagnetic disturbances on the ground. Since the earth is intrinsically conductive, telluric currents are induced, setting up a geoelectric field that can drive unwanted currents in man-made systems.

Recent studies have highlighted the highly-localised nature of the geoelectric field. Our results indicate that dB/dt can vary by several times over just hundreds of kilometres and that this variation can result in up to 60% difference in GICs across a 200 km transmission line. In this work, using geomagnetic observations in Fennoscandia, we report on the localised nature of these disturbances, possible source mechanisms, and how important these are to GIC modelling and prediction. Multi-resolution runs of the Space Weather Modeling Framework are also used to determine how well global MHD can capture these effects.

The implications from our work are: 1) during active intervals, the localised nature of geomagnetic disturbances should be considered when modelling GICs, 2) telluric contributions to dB/dt can be significant, 3) higher resolution runs can give better skill when modelling GICs, and 4) substorms continue to hinder accurate GIC modelling at high latitudes.