# Evaluation of GNSS-TEC Data-Driven IRI-2016 Model for Electron Density
## 4 Discussion and Conclusions
Therefore, based on the experimental results, the grid map of IG-up values in the area of mainland China is provided every day for the relevant engineering practice users to extract the equivalent IG12 values at a specific location and time by using the interpolation method mentioned in the paper, in order to ensure that in the absence of other more effective means (e.g., GNSS, ionosonde) to obtain high-precision ionospheric information, such as the TEC, electron density, peak electron density, and so on, in the region, the IG-up driven IRI-2016 model can be used to achieve the corresponding accuracy requirements. It should be noted that the improvement of the IRI-2016 model in this paper mainly focuses on the mid-latitude region of the Northern Hemisphere, but the ionospheric state varies greatly in different spatial and temporal conditions, especially under severe space weather conditions (e.g., solar radio burst and geomagnetic storms) where the ionospheric variations are exceptionally severe. Although the data of 2015 selected in this paper contains some geomagnetic storm events and achieves better average correction results for the whole year, with the approach of the peak year of the 25 th solar activity week, focusing on the performance of the improved GNSS-based IRI-2016 model (updata-IRI-2016) under this condition has important application value for GNSS navigation and positioning services. In addition, the version of the IRI model used in this paper is IRI-2016, which has been updated to IRI-2020, mainly updating the D-region electron density model, ion temperature model, and the equatorial vertical ion drift model [23]. In this paper, we mainly consider the electron density in the F-region and the corrected model in the Chinese mainland region, so the use of the IRI-2016 model is sufficient to fulfill the purpose of the experiment. However, the IRI model is constantly improving and developing, and we will also apply the future version of IRI to start the model correction work in next work. Conceptualization, writing--original draft, writing--review and editing, J.P., Y.Y., Y.L., H.Z., T.Z., Y.W. and Z.D. ; methodology, T.Z., Y.L. and Y.Y. ; validation, J.P., H.Z., Y.W. and Z.D. ; data curation, J.P., Y.L., Y.W. and Z.D. ; formal analysis, J.P., Y.Y., H.Z. and T.Z. ; funding acquisition, J.P., Y.W. and Z.D. All authors have read and agreed to the published version of the manuscript. This research was funded by the Science and Technology Project of the China Southern Power Grid Yunnan Power Grid Company Ltd., grant number. YNKJXM20220033. Not applicable. **Data Availability Statement:** Fortran version of the IRI-2016 source code from the IRI model official website ([[http://irimodel.org/](http://irimodel.org/)]([http://irimodel.org/](http://irimodel.org/)), accessed on 3 July 2024). COSMIC occultation data are available from CDAAC ([[https://data.cosmic.ucar.edu/gnss-ro/](https://data.cosmic.ucar.edu/gnss-ro/)]([https://data.cosmic.ucar.edu/gnss-ro/](https://data.cosmic.ucar.edu/gnss-ro/)), accessed on 3 July 2024). We acknowledge the data from the Chinese Meridian Project. We would also like to thank the anonymous reviewers for their helpful suggestions. [PERSON], [PERSON], and [PERSON] were employed by the Yunnan Power Grid Company Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest.