Open Magnetic Flux in the Time-Evolving Corona

Models of the Solar Corona, ranging from potential field source surface (PFSS) to magnetohydrodynamic (MHD), typically provide a steady-state representation for a given time period, based on a single photospheric magnetic map.  However, the Sun's magnetic flux is in truth constantly evolving, and these changes in the flux affect the structure and dynamics of the corona and heliosphere.  The dynamics may be crucial to understanding solar wind properties.  A key question in the "Open Flux Problem" is whether the nature of open magnetic flux is adequately captured by steady-state PFSS and MHD models.  We describe an approach to evolutionary models of the corona and solar wind, using time-dependent boundary conditions.  We use the Lockheed Surface Flux Transport (SFT) model to evolve the surface magnetic fields, which in turn drive the coronal evolution.  The simulations are performed with the MAS thermodynamic Wave-Turbulence Driven (WTD) model for a month of simulated time.  We use the simulated observables derived from the simulation to explore the evolution of coronal structure (e.g., coronal hole boundaries).  We investigate the open magnetic flux in the model and contrast the results with MHD solutions using static magnetic flux boundaries at selected times.