## 4 Discussion
Overall, these results are in good agreement with the incoherent radar--IRI comparisons presented in [58]. In order to assess the performance of the IRI-2020 model in representing a real shape of electron density vertical distribution, we additionally compared our reference EDPs from the ionosonde and COSMIC-2 model with the IRI-2020 model simulation results generated with user-specified input of the F2 layer peak parameters (foF2 and hmF2). For this case, we used the real values of foF2 and hmF2 from our reference profiles to adjust the main anchor point in the IRI model formulation to the real parameters of the ionospheric peak. Figure 8 presents the results of standard and adjusted versions of the IRI model outputs compared with the RO-ionosonde combined EDPs. We selected a few representative cases for daytime ionosphere conditions and overplotted the reference combined EDPs (indicated by bluegreen lines describing ionosonde and RO parts), standard IRI EDP output (black  
Figure 7: Comparison of the electron density profiles derived from the IRI-2020 (black line) and the reference profiles combined from ionosonde (blue) and COSMIC-2 RO (green) measurements. Panels (**a–d**) corresponded to the October 2022 high-rate campaign observations and panels (**e–h**) corresponded to the March 2024 campaign. line), and adjusted IRI profiles with user-specified F2 layer peak parameters derived from the corresponding combined EDPs (red dots). Top and bottom panels in Figure 8 illustrate cases corresponding to the October 2022 and the March 2024 campaigns, respectively. The obtained results demonstrate clear differences in the EDPs' shapes and peak values (up to 20% in density) in the model simulation outputs between the standard IRI and the corrected version with the real F2 layer peak values. The data-model discrepancies in the standard IRI outputs for the F2 peak values near the same local time on two consecutive days can result from the climatological nature of the model, driven by monthly averaged solar activity indices, which cannot reproduce accurately day-to-day ionospheric variability. When we adjusted the model ingesting the real observations even in single anchor points at the F2 layer peak, the absolute data-model differences became essentially smaller, especially around the main peak of ionospheric variability. Figure 8: Comparison of the IRI-2020 adjusted EDPs (red dots) with reference combined EDPs (blue-green line). The standard IRI output is shown as a black line. Panels (**a,b**) corresponded to the 24–25 October 2022 afternoon conditions and panels (**c,d**) corresponded to the 19–20 March 2024 noon hours. ionization. With this adjustment approach, we can better depict differences between observations and models in the bottomside ionosphere (E-F layers range), as well as in the topside ionosphere above the F2 layer peak up to \(\sim\)500 km altitude, where we still have real observations. The biggest data--model discrepancies were found for the October 2022 moderate solar activity period. The model overestimated plasma density for the bottomside ionosphere by up to 45% (140-180 km altitudinal range). Above the F2 layer peak, the model also tended to overestimate observations by up to 15%. For the high solar activity (March 2024) and near noon hours, the data-model discrepancies with adjusted IRI were also mainly pronounced in the bottomside of the profile, but estimated differences did not exceed 10%, and the model tended to underestimate measurements there. The obtained results demonstrate a significant discrepancy in most cases for the standard IRI model output both in absolute values of electron density and in altitudes. At the same time, we found pretty good agreement between the adjusted IRI profiles within an altitudinal range of \(\sim\)\(\pm\)50 km around the F2 layer peak and the reference values, but some noticeable discrepancies exist in the topside and bottomside parts of the ionospheric plasma density vertical distributions.