Description
Understanding the evolution of the complex magnetic fields found in solar active regions is an active area of research. There are numerous models for such fields which range in their complexity due to the number of known physical effects included in them, the one common factor being they all extrapolate the magnetic field up from the photosphere. In this study we focus on the fact that above the photosphere and below the corona lies the relatively cool and dense chromosphere -- which is often neglected in coronal models due to it being comparatively thin and difficult to model. We describe a series of 2.5D and 3D simulations using both MHD and magnetofriction which seek to isolate these effects, including a new method for automated boundary driving using SHARP magnetogram data. We find that including a cool and dense stratified layer can result in significant changes to the dynamics of an erupting field far higher in the atmosphere than the chromosphere itself, generally delaying eruptions and resulting in flux rope equilibrium positions much lower in the corona than if it is neglected. In the analysis of these fields we make extensive use of topological quantities such as the winding and field line helicity to investigate the complex structures that form as a result.
