Impulsive Geomagnetic Events and Space Weather Implications

Abstract:

Impulsive changes in geomagnetic fields have been found to be associated with Space Weather impacts on ground-based technological infrastructure. Geoelectric fields associated with these impulsive events have been found to excite geomagnetically induced currents (GIC) and produce harmonic distortion of transformer voltages. Many of these impulsive events have been found to have significant vertically-directed components indicative of vorticity in ionospheric current systems, and possibly field-aligned currents. We have developed an algorithm for the selection of impulsive geomagnetic events to select for large perturbations in geomagnetic components (> 50 nT) over short time periods (< 10 minutes). Cataloging events occurring in the AUTUMNX magnetometer array in 2015-2020, we determine the local-time distribution of impulsive events at a variety of magnetometer stations ranging from subauroral through cusp latitudes. Distributions of these impulsive events find significant peaks in activity in pre-midnight and post-midnight sectors, indicating possible substorm association. Comparisons between the local-time distributions of impulsive geomagnetic events in ground-based magnetometers and of proximal harmonic distortion events are also conducted.