Characterization of Transient Geomagnetic Fluctuations and Associated
Rapid Ionospheric Currents
Abstract
Disturbances in the magnetosphere-ionosphere system cause changes in the
geomagnetic field that result in ground induced currents (GICs) that are
potentially hazardous to electrical systems on Earth. Harmful GICs are
driven by magnetic field fluctuations with timescales generally falling
in the range of 1-10 minutes; much less attention has been placed on
geomagnetic field fluctuations with short timescales (< 60
seconds) because they cause transient induced currents (TICs) that have
not been considered to pose a legitimate threat to electrical systems
since they are similar to electrical transients due to lightning. On the
contrary, short-timescale magnetic field fluctuations have been found to
be capable of coupling directly to power grids and electrical systems,
inducing substantial voltages without first flowing in the ground. This
ionospheric current coupling poses a potential threat to any of these
systems, especially electronic equipment with low operating voltage or
that does not have surge protection. Transmitting devices that are at
risk by such currents are becoming increasingly more prevalent in
society with the growth of the Internet of Things (IoT) network. Our
characterization of transient magnetic field perturbations provides
detail on short-timescale changes of the magnetosphere-ionosphere
coupled system and supports the assessment of possible hazards to
technological infrastructure on Earth. This research is enabled by
modern magnetometers, both ground- and space-based, with high sampling
rate capabilities that allow for the measurement of transient surface
magnetic field fluctuations with short-timescales. We present the
characteristics of transient magnetic field changes observed by the
MACCS array in Arctic Canada by selecting events recorded on the ground
and analyzing the behavior of the electromagnetic fluctuations within
the ionosphere and magnetosphere during such events.