The Dynamic Evolution of Active Region Magnetic Fields in the Solar Atmosphere W.P. Abbett, G.H. Fisher, B.T. Welsch, and D.J. Bercik Space Sciences Laboratory, Univ. of California, Berkeley Corresponding author email: abbett@ssl.berkeley.edu AGU-SPD, May 2008 ABSTRACT: We present a progress report on our efforts to extend the quiet Sun models of Abbett (2007) to active region spatial scales. Our goal is to introduce strong active region magnetic fields into a semi- realistic model of the upper convection zone and atmosphere and to study the evolution of magnetic structures as flux emerges, and interacts with granular motions at the visible surface. The dynamic evolution of active regions will be studied using the fully compressible, 3D MHD code RADMHD, which is capable of including the upper convection zone and low corona within a single computational volume. The initial stages of this numerical investigation necessarily involve technical improvements to the code’s algorithm and enhancements to our treatment of the energetics of the MHD system as we transition from convective dynamo-generated quiet Sun magnetic fields to strong, large-scale active region fields.