## 4 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & \multicolumn{3}{c}{**2015**} & \multicolumn{3}{c}{**2017**} & \multicolumn{3}{c}{**2020**} \\ \hline \multirow{2}{*}{**Period of Time**} & **31** & **31** & **31** & **31** & **31** & **31** & **31** & **31** & **31** & **31** \\  & **January** & **March** & **July** & **January** & **March** & **July** & **January** & **March** & **July** \\ \hline Mean S4 & 0.19 & 0.21 & 0.19 & 0.17 & 0.18 & 0.17 & 0.13 & 0.15 & 0.12 \\ \hline Max S4 & 0.35 & 0.49 & 0.35 & 0.34 & 0.34 & 0.41 & 0.27 & 0.42 & 0.39 \\ \hline RMSE & 0.022 & 0.024 & 0.022 & 0.019 & 0.022 & 0.018 & 0.015 & 0.016 & 0.013 \\ \hline R-Squared & 0.81 & 0.80 & 0.81 & 0.81 & 0.80 & 0.81 & 0.83 & 0.82 & 0.85 \\ \hline Scintillation Occurrence (S4 \textgreater{} 0.2) & 48\% & 53\% & 47\% & 39\% & 43\% & 39\% & 9\% & 10\% & 7\% \\ \hline \end{tabular}
\end{table} 
Table 2: The difference between predicted and observed S4 values during 24 h on 31 January, 31 March, and 31 July in 2015, 2017, and 2020. Figure 3: The predicted and observed S4 during 24 h on 31 January, 31 March, and 31 July in 2015, 2017, and 2020.  
modeling compared to 2015 and 2017. The lowest ROTI modeling accuracy among these three years belongs to the 30 days of March 2015, and the highest modeling accuracy is for the 30 days of July 2020. In the next step, ROTI values are predicted using the GANN model for the day after the 30-day modeling period. For this purpose, the physical parameters related to the ionospheric irregularities mentioned in the previous sections are used for the prediction day as input data. Then, the ROTI is predicted for the desired time interval using the GANN-trained model. Table 4 represents the predicted values for 31 January, 31 March, and 31 July for the ROTI parameter in 2015, 2017, and 2020. As stated in Table 4, the highest observed ROTI is in 2015, followed by 2017 and 2020, respectively. This trend is similar to the average trend of the S4 observed at the same time. According to the average of VTEC observed, it can be seen that mean VTEC values in 2015 were higher than those in the other two years, which indicates the higher solar magnetic activity of that year. Furthermore, 2015, 2017, and 2020 have the highest maximum VTEC and the highest average VTEC. Among the months of each year, March has the highest ROTI and observed VTEC. The highest average ROTI and VTEC observed for these three years are equal to 1.67 and 39.95 TECU, on 31 March 2015. On 31 January and then 31 July, the next highest observed ROTI and VTEC are recorded. The VTEC and ROTI observed in 2020 represent the lowest observed ROTI and VTEC among all predicted days. The lowest means of the ROTI and VTEC observed on 31 July 2020 are equal to 0.73 and 9.78, respectively. Regarding the accuracy of the prediction and the accuracy of modeling, as it can be seen, the accuracy trend for the prediction phase is similar to the modeling stage, i.e., the accuracy of the prediction for the intervals with more accurate modeling is higher. The average observed ROTI value is similar to the modeling trend. Similar to the S4 and ROTI, the R-square and RMSE decrease with a reduction in solar magnetic activity.