Modelling the topside ionosphere: improving NeQuick through radio occultation data

Speaker: Alessio Pignalberi (Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy)

Abstract: The topside ionosphere is the region of the upper atmosphere extending from the F2-layer peak to the plasmasphere. This is the environment where low-Earth-orbit satellites live, and it also highly affects the propagation of GNSS signals. Hence, its description has gained more and more importance in the last years. However, the modelling of the electron density distribution in this region represents still a challenge for the ionospheric community. This presentation describes novel methodologies developed to improve the NeQuick model topside ionosphere formulation by taking advantage of electron density observations by radio occultation. The NeQuick topside formulation is mathematically inverted to derive a fully analytical expression of the topside effective scale height, which is then used to optimize the NeQuick topside parameters. Through a large dataset of radio occultation observations, we highlighted the main spatial, diurnal, seasonal, solar and magnetic activity variations of the NeQuick topside parameters, and provided a first application for topside ionosphere modelling.