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

Modelling the topside ionosphere: improving NeQuick through radio occultation data

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.

_{Bio: Alessio Pignalberi obtained the PhD degree in Geophysics from the University of Bologna in 2019, and from 2019 onwards he is post-doctoral fellow at the Italian National Institute of Geophysics and Vulcanology (INGV) in Rome. Since his PhD, he is deeply involved in the field of ionosphere modelling by improving empirical climatological models like the International Reference Ionosphere (IRI) and NeQuick. He is the main author of the IRI UP data assimilation method, and most of his research activity is currently devoted to the modelling of the topside ionosphere. He was awarded with the International Union of Radio Science (URSI) Young Scientist Award in 2017 and 2021.}