The time derivative of the geomagnetic field has a short memory

Abstract. Solar eruptions and other types of space weather effects can pose a hazard to the high voltage power grids via geomagnetically induced currents (GICs). In worst cases, they even cause large-scale outages. GICs are complex phenomenon, closely related time derivative geomagnetic field. However, behavior is chaotic has proven be tricky predict. our study, we look at dynamics field during active weather. We try characterize magnetic behavior, better understand drivers behind strong GIC events. use data from IMAGE (International Monitor for Auroral Geomagnetic Effect) magnetometer network between 1996 2018. The measured primarily produced by in ionosphere magnetosphere, secondarily conducting ground. separated analysis. separation means that computationally divided into external internal parts corresponding ionospheric telluric origin, respectively. study yearly directional distributions baseline subtracted, horizontal field, ?H, its derivative, d?H/dt. do not have clear solar cycle dependency. more scattered than There also clear, station-specific differences sharp conductivity contrasts continental ocean regions or inland anomalies. One main findings direction d?H/dt very short “reset time“, around 2 min, but ?H does this kind behavior. These results hold true with less conditions. conclude result gives insight scale current systems, which primary driver derivative's It emphasizes persistence compared highlights challenges forecasting (and GIC).