A global empirical model of the ionospheric topside electron density

As it was mentioned in many publications, the Bent model for the topside ionosphere used in IRI is not adequate, especially for the periods of high solar activity. Additional efforts are necessary to improve the empirical presentation of the electron concentration vertical distribution in topside ionosphere. The present paper is review of attempts to create the empirical model of the topside vertical profile undertaken within the frame of IRI Task Force Activity Workshops held at ICTP, Trieste. The Intercosmos-19 topside profiles database was used. The profile was approximated by Epstein function with the altitude dependent F2 layer thickness parameter B2u. The main task was to find if the latitudinal dependencies of the model parameters have the regular character. The model was presented as the set of coefficients characterizing the profile for different latitudes, season and local time. Up to now the model is limited by the period of high solar activity. Attempts were made on revealing the longitudinal dependencies and its inclusion in the model.