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Review of Forecasting the Critical Frequency of the Ionospheric F2 Layer

This literature review considered journals published over the last five years as primary references in the field of forecasting ionospheric F2 layer critical frequency (foF2) under quiet and disturbed conditions using neural networks and particle swarm optimisation algorithm. The literature was extracted on the basis of the search results and then divided into two major domains: principles of ionospheric critical frequency and methods for forecasting foF2. The proposed differentiation enables future research on factors that affect the variability of foF2 and on techniques used in foF2 prediction, such as empirical and neural network models. Thus, neural networks can be used to investigate and develop improved foF2 models