Location of geomagnetic disturbances in relation to the field aligned
current boundary.
Abstract
Geomagnetic disturbances (GMDs) are rapid fluctuations in the strength
and direction of the magnetic field near the surface of the Earth which
can cause electric currents to be induced in the ground. The
geomagnetically induced currents (GICs) can cause damage to pipelines
and power grids. A detection algorithm has been developed to identify
rapid changes in 10 second averaged magnetometer data. This higher
resolution data is important in capturing the most rapid changes
associated with extreme GIC events. The algorithm has been used on an
array of ground-based magnetometers from SuperMAG data from 2010 to
2022, creating a new list of global GMDs. Data from the Active
Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE)
is used to place the observed GMDs in the context of the global pattern
of magnetosphere-ionosphere field-aligned currents (FACs). A dawn sector
population of GMDs is found to lie near the boundary between the region
1 and region 2 FACs, while a pre-midnight sector population is found to
occur poleward of the FAC boundary on region 1 upward FACs. It is also
shown that the latitude of the GMDs expands with the FAC boundary and
their occurrence peaks around 77 degrees magnetic latitude.