  Intense currents produced during geomagnetic storms dissipate energy in the
ionosphere through Joule heating. This dissipation has significant space
weather effects, and thus it is important to determine the ability of
physics-based simulations to replicate real events quantitatively. Several
empirical models estimate Joule heating based on ionospheric currents using the
AE index. In this study, we select 11 magnetic storm simulations from the CCMC
database and compare the integrated Joule heating in the simulations with the
results of empirical models. We also use the SWMF global magnetohydrodynamic
simulations for 12 storms to reproduce the correlation between the simulated AE
index and simulated Joule heating. We find that the scale factors in the
empirical models are half what is predicted by the SWMF simulations.
