Key principles of constructing probabilistic statistical ionosphere models for the radiowave propagation problems

It is demonstrated that it is required to create probabilistic statistical models of the ionosphere for calculating radio propagation in a wide frequency range. This, in fact, presents a new type of ionospheric modeling. These models are classified into pure statistical and deterministic-stochastic. We describe the key principles of building such models, present some examples of their construction, and discuss some difficulties arising from them.