ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: a significant challenge. The initial magnetic and thermodynamic configuration (i.e., densities, pressures, and temperatures imposed on the system) is critical to the initial force balance of the system, particularly in the layers at and directly above the model photosphere. Unless this initial state is constructed in a physical way, where the pressure gradients act to balance the forces from magnetic pressures and stresses acting to push apart concentrations of field, nonphysical flows and dynamics will eventually dominate any driving forces imposed at the photosphere. This is a particular problem with the zero- β approach because the only possible restorative forces in these regions are due to Reynolds and viscous stresses. On the Sun, the observed evolution of the magnetic field in the photosphere and low atmosphere results from a complex interaction of fields and flows in a gravitationally stratified, turbulent environment. But there is insufficient observational information available to adequately specify the dynamic and thermodynamic initial state of the system. In standard ab initio models of magnetic flux emergence or magnetoconvection, one is not faced with this difficulty. Typically, field-free thermodynamic states are developed in a physical way through a dynamic and energetic relaxation process, and stratification in density, pressure, and temperature naturally results from the presence of gravity and the application of physical boundary conditions. Once this relaxation procedure is complete, only then is magnetic field introduced into the system. In the case of data driving, we are presented with the opposite scenario. We are given an initial magnetic field and an electric field to be applied to the model’s photospheric boundary, with little to no information regarding the hydrodynamic state of the plasma in the low atmosphere where such information is necessary to drive the dynamics of the system in a physical way. So how best to proceed? We find that there are two ways to address this initialization problem: the first is to simply scale the fields and place the lower boundary of the simulation in the upper transition region or corona, thereby placing the driving layer in a field-filled, magnetically dominated regime. The second is to keep the driving layer in the photosphere, generate an initial thermodynamic stratification, and artificially limit nonphysical runaway flows when necessary to mitigate dynamics unrelated to the driving forces of interest. We choose not to pursue the first approach, because we find that photospheric electric fields bear little resemblance to coronal electric fields once magnetic structures have expanded into the low-density, low- β corona. This amounts to ignoring the data in the photosphere altogether in favor of a different, more idealized problem. The second approach involves generating initial thermodynamic states and flow fields by a dynamic relaxation process that holds the initial magnetic