## 5 Results and Discussion
### Comparative and Qualitative Analysis  
In this section of our study, we conducted a detailed visual analysis of the predicted S4 values over a three-day interval at the end of each month, specifically targeting the 29 th, 30 th, and 31 st. The predictions were generated using three distinct ConvGRU models: ConvGRU-L\({}_{\text{C}}\), ConvGRU-L\({}_{\text{log-cosh}}\), and ConvGRU-L\({}_{\text{g}}\). The outcomes of these predictions for the specified days are illustrated in Figures 6-8. For a focused analysis, we selected key diurnal moments--sunrise, noon, and sunset--known for manifesting significant ionospheric variability. These time periods were chosen to capture the dynamic nature of ionospheric changes over the course of a day and night. The geographical focus was set at a median longitude of 300 degE and a latitude of \(-20\arcdeg\)S, positioning our study within the western South American region, near Ecuador and Peru, which typically aligns with the UTC-5 time zone. The graphical representations in Figures 6-8 display both observed and model-predicted S4 values at the designated times of sunrise, noon, and sunset. These visualizations clearly illustrate the disparity in ionospheric behavior between 2015 and 2020. This variation can primarily be attributed to the differing levels of geomagnetic activity observed in these two years, with each model reflecting unique capabilities in capturing these differences. The visual comparisons not only underscore the temporal variations in ionospheric disturbances but also highlight the predictive strengths and weaknesses of each ConvGRU model under varying geomagnetic conditions. Figure 6: Observed and predicted S4 maps for South America on 29 th January in 2015 and 2020 at three time points. The figure displays maps at sunrise (05:45 LT–10:45 UT), solar noon (12:15 LT–17:15 UT), and sunset (18:40 LT–23:40 UT). The first column illustrates the observed S4 values, while the subsequent columns show predictions from the ConvGRU-L\({}_{\rm C}\), ConvGRU-L\({}_{\rm log\,cosh}\), and ConvGRU-L\({}_{\rm S}\) models, respectively. Figure 7: _Cont._  
The observed S4 map on 29 January 2015, at sunrise (05:45 LT-10:45 UT) reveals pronounced ionospheric activity along the equatorial anomaly from approximately 10\({}^{\circ}\)S to 0\({}^{\circ}\), with high-intensity zones around 300\({}^{\circ}\)E longitude, as shown in Figure 6. This time typically experiences enhanced disturbances due to increased solar radiation at dawn. The ConvGRU-L\({}_{\rm C}\) model accurately replicated the intensity and spatial distribution of scintillation zones during this period. Although some areas showed smoothed gradients, this model robustly captured the ionospheric dynamics at sunrise. In contrast, the ConvGRU-L\({}_{\rm log-cosh}\) model captured the broader scintillation activity but tended to dilute peak intensities, potentially overgeneralizing ionospheric conditions. The ConvGRU-L\({}_{\rm S}\) model significantly diverged from observed patterns, underestimating scintillation intensity and misrepresenting high-activity regions, thus displaying lower sensitivity to rapid changes. By noon (12:15 LT-17:15 UT), the overall scintillation intensity decreased, reflecting the typical diurnal reduction in solar radiation effects. Notable activity persisted along the equatorial regions, though less intense and more dispersed than at sunrise. The ConvGRU-L\({}_{\rm C}\) model adeptly adjusted to this shift, accurately maintaining the intensity and geographic specificity. However, the ConvGRU-L\({}_{\rm log-cosh}\) model, while capturing the overall reduction in activity, lacked the granularity to precisely localize the highest scintillation zones. Conversely, the ConvGRU-L\({}_{\rm S}\) model's outputs were subdued and poorly aligned with observed spatial patterns, highlighting its ongoing challenges in accuracy. The sunset map (18:40 LT-23:40 UT) continued to show scintillation activities along the equatorial anomaly.