Ground Magnetic Perturbations Associated with Sawtooth Auroras.

Abstract:

For millennium, humans have been captivated by the light show emanating from Earth’s
magnetic poles. However, it has only been within the last few decades that scientific
understanding has developed over the geomagnetic phenomenon. Remote Earth sensors and
ground-based instrumentation (such as satellites and magnetometers), provide insight behind the
physical process of auroral brightening and expansion, or even creation. Sawtooth aurora (SA) is
one of these prominent aurora structures. However, to date, there is little study on the magnetic
perturbations associated with SA. The objective of this research is to study the SA associated
ionospheric current structures and characteristics of ultra-low frequency waves (ULF) through
the analysis of magnetometer data and advance the science towards a mechanism that interprets
SA. This study examines SA events from the years of 2014 to 2018 as provided in He et al.,
2020, specifically inspecting ground-level magnetic perturbations utilizing the SuperMAG
database. Ground-based measurements were studied along two parameters: magnetic
perturbation (direction and magnitude) and ULF wave powers. For each SA event, multiple
magnetometer stations were chosen near the SA shown through DMSP satellite images. This
provides multiple separate vantage points to study one singular event, results exhibited
distinctive features dependent on the location of the magnetometers. ULF waves in the Pc2 – Pc5
bands provided by SuperMAG are also analyzed to understand the wave activity associated with
SA events