Day-to-day variability of the IRI electron density height profile Original Research Article

The International Reference Ionosphere (IRI) electron density height profile is parametric in terms of anchor point values that are generated either from particular-epoch measurements of the various ionospheric characteristics, or are determined from empirical expressions produced from the fit to past data sets. Such expressions relate to the monthly median or to specific daily percentile values of these quantities. The need for full bottomside profiles corresponding to any chosen probability of occurrence is examined and how these may be derived is addressed. The use in this task of the established Bradley-Bedford expressions relating reference decile or quartile ionosphere characteristics to corresponding values for any required probability is outlined.A key preliminary consideration is to investigate the correlations between individual daily ƒoF2, M(3000)F2, h′F and ƒoE values. The extent to which trends are repetitive is discussed. In the absence of information about the variabilities of all the IRI parameters at the time of writing and as a fore-runner to a full analysis, formulae are presented for a simplified ionospheric model showing how F-region profiles appropriate to particular probabilities of occurrence may be generated.