Characteristics of ephemeral coronal holes

Ephemeral coronal holes are short-lived, low-density regions of the solar corona observed as dark features at EUV wavelengths, and are associated with open magnetic field lines due to a single dominant polarity. These structures are distinct from longer-lived equatorial and polar coronal hole regions, and remain relatively unexplored. Ephemeral coronal holes are primarily characterized by a lifetime substantially less than a single solar disk crossing, typically lasting only a few days. We conduct a systematic search for these events using Atmospheric Imaging Assembly (AIA) data provided by the Solar Dynamics Observatory (SDO), examine their characteristic properties and investigate the relationship with the underlying magnetic field structure. A preliminary examination of the SDO/AIA database between 2010-2016 identified 5 clear examples of ephemeral coronal holes, suggesting that they are rare phemonena. For each event we determine its key properties, including spatial extent over time, growth and decay rates, total lifetime, average flux within the coronal hole, and associated magnetic field properties. We also examine links between the coronal hole evolution and the magnetic network structure in the lower atmosphere. Further research will reveal the prevalence of these apparently rare phenomena, and shed light on the properties of the magnetic field that lead to their rapid formation and dissolution.