Evaluation and correction of the IRI2016 topside ionospheric electron density model

The international reference ionosphere (IRI) is the internationally recommended empirical model. The IRI2016 is now the latest version, and it includes three options for the prediction of topside electron density profiles: IRI2001, a correction of IRI2001 (IRI2001corr), and NeQuick model. In the paper, we use the Arecibo, Jicamarca, and Millstone Hill incoherent scatter radar observed topside electron density data ranging from year 2001 to 2014 to assess the prediction capabilities of these three model options. The results show that the NeQuick model outputs perform best at these areas from the point view of relative difference distribution, followed by the IRI2001corr model, and the IRI2001 option is worst. To further improve the performance of NeQuick and IRI2001corr options, the correction factors are introduced in their model formulation and are determined by the least squares estimation technique. Compared with the original models, the corrected models perform in average better, especially at low and medium solar activities.