The Observational Uncertainty of Coronal Hole Boundaries in Automated Detection Schemes

Solar coronal holes are the observational manifestation of the solar magnetic field open to the heliosphere and are of pivotal importance for understanding the origin and acceleration of the solar wind. Space missions such as the Solar Dynamics Observatory now allow us to observe coronal holes in unprecedented detail. Instrumental effects and other factors, however, pose a challenge to automated detection of coronal holes in solar imagery. The science community addresses these challenges with a variety of detection schemes. Until now, scant attention has been paid to assessing the disagreement between these schemes. Here we present the first comprehensive comparison of widely-applied automated detection schemes in solar and space science. By tying together scientific expertise worldwide, we study a coronal hole observed by the Atmospheric Imaging Assembly instrument on 2018 May 30. We find that the choice of detection scheme significantly affects the location of the coronal hole boundary. Depending on the detection scheme, the physical properties of the coronal hole including the area, mean intensity, and mean magnetic field strength vary by a factor of up to 4.5 between the maximum and minimum values. This presentation discusses the implications of these findings for coronal hole research from the past decade. We also outline future strategies on how to use our results to diagnose and improve coronal magnetic field models.