  It is typically assumed that emission in the passbands of the Atmospheric
Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) is
dominated by single or several strong lines from ions that under equilibrium
conditions are formed in a narrow range of temperatures. However, most SDO/AIA
channels also contain contributions from lines of ions that have formation
temperatures that are significantly different from the "dominant" ion(s). We
investigate the importance of these lines by forward modeling the emission in
the SDO/AIA channels with 3D radiative MHD simulations of a model that spans
the upper layer of the convection zone to the low corona. The model is highly
dynamic. In addition, we pump a steadily increasing magnetic flux into the
corona, in order to increase the coronal temperature through the dissipation of
magnetic stresses. As a consequence, the model covers different ranges of
coronal temperatures as time progresses. The model covers coronal temperatures
that are representative of plasma conditions in coronal holes and quiet sun.
The 131, 171, and 304 \AA{} AIA passbands are found to be least influenced by
the so-called "non-dominant" ions, and the emission observed in these channels
comes mostly from plasma at temperatures near the formation temperature of the
dominant ion(s). On the other hand, the other channels are strongly influenced
by the non-dominant ions, and therefore significant emission in these channels
comes from plasma at temperatures that are different from the "canonical"
values. We have also studied the influence of non-dominant ions on the AIA
passbands when different element abundances are assumed (photospheric and
coronal), and when the effects of the electron density on the contribution
function are taken into account.
