LASP Magnetosphere Seminars

Abstract

Geomagnetically Induced Currents (GICs) are currents generated in power grids and other long conductive structures during geomagnetic storms. Rooted in Faraday’s law of induction, these currents arise from time-varying magnetic fields that induce electric fields in the ground. While GICs are a well-known space weather hazard, their behavior is complex and often highly localized, shaped by both magnetic field fluctuations and regional ground conductivity. In this seminar, I will present case studies that demonstrate a new framework combining wavelet analysis of GIC signals with data fusion from ground- and space-based observations. This approach allows us to identify and understand localized magnetosphere-ionosphere (M-I) coupling processes that drive ground magnetic perturbations. A key finding from my published work shows that periodic GIC spikes in Finland were linked to the braking of Bursty Bulk Flows around 4 Earth radii (Re) in the dusk sector—without any clear upstream solar wind trigger. In the U.S., GIC measurements have only recently become more widely available, with a centralized database beginning in 2013. Analyzing this emerging dataset offers valuable insights into mid-latitude GICs, which remain relatively understudied. I will share preliminary results from two case studies: (1) During the 7–9 September 2017 event, I show that ionospheric conditions—particularly as a function of local time—play a key role in producing distinct GIC waveforms at three different global locations; and (2) In the 12 May 2021 event, I examine the sequence of processes that led to long-duration elevated GICs in the dawn-to-noon sector. Our analysis suggests that enhanced electric field penetration during undershielding conditions was the primary driver. Due to the limited availability of direct GIC measurements, many studies rely on the time derivative of the magnetic field (dB/dt) as a proxy. I will conclude by discussing the limitations of this assumption and why direct GIC observations, where available, are critical for understanding the true geoelectric impact of space weather events.