A novel concept for empirical D-region modelling Original Research Article

Reliable data in the D-region are essentially restricted to measurements by rocket-borne radiowave propagation experiments. Analytical descriptions of lower ionosphere electron densities have to be built around only 120 such electron density profiles. A complex function that can potentially describe non-linear dependencies of the electron concentration as a function of e.g. the solar zenith requires a complexity that the small number of available measurements can not yield. In a novel approach D-region electron densities are calculated for a large number of conditions using a relatively simple steady-state ion-chemical model. The rocket data are used to establish an empirical correction to the theoretical values. This analytical correction model can be of a much lower mathematical order since the complex structure is taken care of by the ion-chemical description. The resulting deviations of first versions of this model are a little smaller than those of previous versions, more importantly, they are more uniform with altitude compared to previous attempts to fit these rocket data by a simple analytical description.