SOLARNET Conference: The Many Scales of the Magnetic Sun

Coronal holes are temporary regions in the solar corona that appear dark in extreme ultraviolet (EUV) and soft X-ray solar images. They have low densities, temperatures, and intensity emissions in comparison to non-coronal hole regions. Magnetic fields within coronal holes are open and unipolar; they originate from the photosphere and extend into interplanetary space. These open magnetic field lines play a significant role in the formation and evolution of coronal holes, allowing plasma to escape into space. The origin of open magnetic flux is still an open question in solar physics. We measure and analyse the photospheric magnetic field below the coronal holes using line-of-sight magnetogram data to understand the footprint of open magnetic flux in the coronal holes. Our preliminary results show that equatorial coronal holes have a unipolar magnetic field that does not evolve drastically with time. We also found that the magnetic skewness of coronal holes is significantly different than the quiet sun, but the skewness is consistent across half of the solar disk.