## 3 Results and Discussion  
### CEJ Occurrences Based on Local Times, Solar Activity Levels, and Seasons  
The CEJ analysis results presented in this section were described according to local times, solar activity levels, and seasons. In Figure 4a,b, the occurrence percentages at DAV, which represented the east, were plotted alongside the solar flux index (F10.7) for MCEJ and ACEJ, respectively. Meanwhile, the pie charts in (c) and (d) show each CEJ type's occurrence percentages for low and high solar activity. Information in (e)-(h) is similar to (a)-(d) but for the LKW station which represents the west. Figure 3: Number of observation days for 11 years of solar cycle 24 from different stations. Figure 2: Examples include (**a**) MCEJ and ACEJ at DAV on 24 January 2018, and (**b**) PSD at DAV on 10 August 2017. Considering the years and solar activity levels, MCEJ and ACEJ in the east accounted for 70%, and 30% of the total detected CEJ. It was apparent that the prominent type of CEJ (the MCEJ) correlated well with F10.7 index values and occurred frequently (80-100%) during higher values (i.e., 2011-2014) compared to lower values (i.e., 2008-2010, 2016-2018). The opposite was observed for ACEJ, where the percentage dropped from 55% during lower index values to less than 20% during higher index values. The dependencies were quantified, supported by calculating the correlation coefficient, R, with R \(\geq\) 0.6 being strongly correlated and R < 0.6 being weakly correlated [23]. MCEJ and ACEJ were positively (R = 0.95) and negatively (R = \(-\)0.95) correlated to the F10.7 index. Figure 4c,d shows that the dominant MCEJ increased from 59% during low to 91% during high solar activity levels. CEJ dependency on the F10.7 index in the western part was quite similar to the east. According to Figure 4e,f, MCEJ occurred more frequently (30-70%) during the higher index than during the lower index (<40%), which is consistent with the observations in the east. In contrast, the ACEJ percentage reduced slightly from 90% during the lower index to less than 70% during the higher index. Correlations with the F10.7 index were found to be weaker compared to the east, with R = 0.77 for MCEJ and R = \(-\)0.78 for ACEJ, indicating moderate correlations. As afternoon type dominated 80% of CEJ events in the west, more ACEJs than MCEJs were observed for both solar activity levels, as illustrated in Figure 4g.h. An outstanding correlation obtained in the presented results indicated that CEJ was highly dependent on solar activity. This is the first time such observation was reported for the Southeast Asian sector after observations during solar cycle 19 and 20 years in prior investigations could not be ascertained due to insufficient data and a small number of events [24]. Additionally, a novel finding and noteworthy contribution of the present work was the east-west asymmetrical behavior: the morning type's dominance in the eastern part, DAV (consistent with a previous observation [10]), and the afternoon type's dominance in the west, LKW. This asymmetricity might be induced by the EEJ of varying strengths at different locations as CEJ tend to be inhibited if strong EEJ occur [25]. More convincingly, a recent study in the same region had also discovered stronger EEJ at LKW  
Figure 4: Percentage occurrences (left y-axis) of (**a**) MCEJ and (**b**) ACEJ at east (DAV) alongside F10.7 index (right y-axis) throughout solar cycle 24, as well as the overall percentages of both types of CEJ categorized into (**c**) low and (**d**) high solar activity levels. Information in (**e**–**h**) is similar to (**a**–**d**) but for the west (LKW). than at DAV, regardless of solar activity levels [23]. For that reason, a more detailed case study regarding the EEJ strength influence on CEJ types can be performed as a continuation of the current work to confirm the assumption.