Although a variety of phenomena may create a geomagnetic storm on Earth, the most severe geomagnetic storms arise from solar activity, and in particular, coronal mass ejections (CMEs) and solar flares. CMEs and flares originate primarily from sunspots. The "aa index" is a metric which ranks all of the strongest geomagnetic storms between 1868 and 2010 based on a variety of characteristics taken from several sources. This paper examines correlations between the aa index of the most severe geomagnetic storms and the intrinsic characteristics of the sunspots from which they originated. We find a correlation between the total rank of the aa index of the storms and the "total intensity" of the sunspot, where total intensity is defined as the sunspot's mean intensity multiplied by its area. The correlation has an R-Squared = 0.690 and R-Squared = 0.855 when a potentially corrupted data point is removed.
@article{arxiv.2308.09848,
title = {An Optical Analysis of Sunspots as Predictors of Geomagnetic Storms},
author = {Matthew Shelby and Scott Scharlach and Petar Matejic and RJ Everett and Colton Morgan},
journal= {arXiv preprint arXiv:2308.09848},
year = {2023}
}