Non-equilibrium ionization in the transition region network
The consequences of the persistent downflow of material within the supergranule network of the sun are examined. An accepted temperature model and two models of velocity fields are used to determine the ion distributions of carbon, nitrogen, and oxygen throughout the transition region and to compare them with equilibrium distributions. Attention is given to how the temperature model must be modified in order to reconcile the computed line intensities with observed intensities; it is shown that a small temperature gradient, and possibly a different pressure distribution, are required. It is demonstrated that the observed downflow is probably adequate to overcome the tendency for thermal diffusion to establish concentration gradients; thus the downflow keeps the atmosphere well mixed.