Global Comparison of F2-Layer Peak Parameters Estimated by IRI-2016 With Ionospheric Radio Occultation Data During Solar Minimum

The F2-layer peak parameters of the International Reference Ionosphere (IRI) model are critical to its subsequent applications because of the vital role of the peak parameters in determining other IRI model outputs. Therefore, we analyzed the statistical deviation and ionospheric climatology of NmF2/hmF2 between the most current version of the IRI model, namely IRI-2016, and ionospheric radio occultation (IRO) data, including Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) and FengYun-3C (FY3C), during the recent solar minimum in 2017-2019. The International Union of Radio Science (URSI) model for F2-layer peak electron density (NmF2) and the Bilitza-Sheikh-Eyfrig (BSE), Altadill-Magdaleno-Torta-Blanch (AMTB), and SHUbin (SHU) models for maximum ionization height (hmF2) in IRI-2016 are compared with the IRO dataset. A statistical analysis shows a systematic offset of less than 10% in NmF2 between IRI-2016 URSI and IRO data, and the SHU option for hmF2 shows a better fit to IRO data than BSE and AMTB. A climatology comparison shows that NmF2 estimated by IRI-2016 URSI is consistent with that of the IRO dataset in terms of the general trend in the typical ionospheric characteristics; except for some discrepancies in the marine area, the IRO data may provide a feasible reference for IRI estimation in marine regions. The hmF2 options of BSE/AMTB/SHU show hemispheric asymmetry like the IRO dataset. Moreover, hmF2 of BSE/AMTB and IRO/SHU show some discrepancies in fine structures, such as the day-night reversal phenomenon.