Topside electron density in IRI and NeQuick: Features and limitations

The topside ionosphere modeling suffers from the relative scarcity of experimental electron density data. Different modeling approaches have been applied in empirical models, like IRI, and profilers, like NeQuick. Comparing ISIS-2 topside electron density profiles with IRI and NeQuick models weak points in their topside formulation are identified and analysed. The IRI topside consists in two constant gradient sections, with a transition height kept at a fixed height in its domain. Tests of transition height and gradient 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. An alternative formulation is presented based on k values derived from experimental profiles.