Models of the solar corona typically simplify the energy equation by neglecting important energy transport processes. These "polytropic" models are useful but also have significant limitations. Through scientific and technical advances enabled by CISM, we have significantly improved our coronal modeling capability to include the effects of coronal heating, the conduction of heat parallel to the magnetic field lines, radiative losses, and the acceleration of the solar wind by Alfven waves.

We refer to this as the "thermodynamic" MHD model. A principal difficulty in this type of model is related to the extremely steep temperature and density gradients in the transition region, a consequence of the balance between conduction of heat from the hot corona and radiation loss in the transition region. Recent work on the MAS coronal model has provided an important advance that effectively treats the transition region as slightly broadened without compromising the coronal solution.

The more accurate representation of energy flow in the thermodynamic MHD model produces a significantly better estimate of the plasma temperature and density in the corona, and allows us to compute simulated EUV and X-ray emission as would be observed from instruments such as SOHO EIT and Yohkoh SXT.