Topside electron denstity in IRI and NeQuick models

The modelization of the topside ionosphere suffers of the relatively scarcity of electron density experimental data. Different modelling approaches have been applied in empirical models, like IRI, and profilers, like NeQuick. Comparing ISIS2 topside electron density profiles with IRI and NeQuick models weak points in their topside formulation are identified and analyzed. The IRI topside consists in two constant gradients sections, with a transition height kept at a fixed height in its domain. Tests of transition height and gradients modifications are presented, based on experimental evidences and model efforts. NeQuick model has a topside formulation based on a semi-Epstein layer, governed by an empirical shape parameter k. Alternatives of k formulation improvements are presented based on k values derived from experimental profiles and slab thickness behavior.