# A Spatial Reconstruction Method of Ionospheric foF2 Based on High Accuracy Surface Modeling Theory
## 5 Conclusions  
In this study, we introduced a novel technique named the HAS method for spatial reconstruction of the foF2 region. The foF2 ionospheric parameter of seven ionospheric stations in Oceania was reconstructed in sequence under different solar activity epochs, seasons, and local times, and the foF2 predicted data were compared with the actual data to verify the validity of the HAS method. Moreover, the prediction accuracy of the HAS model was compared with the IRI prediction model and Kriging interpolation method, and it was verified that the HAS method improved the accuracy. The validation results indicate that during different solar activity periods, the HAS method predicted the foF2 with a smaller RRMSE of 7.74% during moderate solar activity periods, which represented an improvement of 7.41% in prediction accuracy compared with the Kriging interpolation method. Across the four seasons, the HAS method predicted the foF2 with a smaller RRMSE of 8.09% in winter, showing a prediction accuracy which aligned closely with the actual observations from ionospheric stations, which had an RRMSE of 10.20%. The HAS method's prediction accuracy improved by 12.00% compared with that of the Kriging method. At different times, the HAS method predicted the foF2 with a smaller RRMSE of 9.23% during moderate solar activity periods, representing a 5.92% improvement in prediction accuracy compared with that of the Kriging interpolation method. The average RRMSE of the IRI prediction model under the validation dataset was 12.35%, and the prediction accuracy of the HAS method improved by 2.06% compared with that of the IRI prediction model. These results demonstrate the correctness and effectiveness of the proposed HAS method.  
Conceptualization, [PERSON] and [PERSON]; methodology, [PERSON] and [PERSON]; software, [PERSON], [PERSON] and [PERSON]; validation, [PERSON] and [PERSON]; formal analysis, [PERSON], [PERSON] and [PERSON]; investigation, [PERSON], [PERSON] and [PERSON]; resources, [PERSON]; data curation, [PERSON], [PERSON] and. Y.S.; writing--original draft preparation, [PERSON] and [PERSON]; writing--review and editing, [PERSON] and [PERSON]; visualization, [PERSON] and [PERSON]; supervision, [PERSON], [PERSON] and [PERSON]; project administration, [PERSON]; funding acquisition, [PERSON] All authors have read and agreed to the published version of the manuscript.  
Figure 9: Comparison of reconstruction results. **(a)** The reconstruction outcomes of the HAS method at 12:00 p.m. local time for the high solar activity high in November 2014. **(b)** The reconstruction outcomes of the Kriging method at 12:00 p.m. local time for the high solar activity year in November 2014. **(c)** The reconstruction outcomes of the HAS method at 12:00 a.m. local time for the high solar activity year in July 2018. **(d)** The reconstruction outcomes of the Kriging method at 12:00 a.m. local time for the high solar activity year in July 2018. **(e)** Distribution of the RRMSEs of the HAS method in predicting the seven stations at 12:00 p.m. local time for the high solar activity year in November 2014. **(f)** Distribution of the RRMSEs of the Kriging method in predicting the seven stations at 12:00 p.m. local time for the high solar activity year in November 2014. **(g)** Distribution of the RRMSEs of the HAS method in predicting the seven stations at 12:00 a.m. local time for the low solar activity year in July 2018. **(h)** Distribution of the RRMSEs of the HAS method in predicting the seven stations at 12:00 a.m. local time for the low solar activity year in July 2018.  
**Funding:** This research was funded by the National Natural Science Foundation of China under grant no. 62031008 and the State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information Systems under grant no. CEMEE2022G0201.  
**Data Availability Statement:** No new data were created or analyzed in this study. Data sharing is not applicable to this article.  
**Conflicts of Interest:** The authors declare no conflicts of interest.