## Appendix C Global Distributions of TEC and Electron Density from CSES-01 Satellite  
In this section, we present the global distributions of _TEC_ obtained from GIM data. Instead of showing the _TEC_ at a defined UT (the original data), we preferred to interpolate the data at 2:00 AM local time for all the longitudes of the world. Not all the values are interpolated if the data at 2 LT is available for the specific longitude. Otherwise, it is linearly interpolated from the previous and following GIM map, including the last value of the day before (22 UT) and first value (0 UT) for the following day. The reason to choose 2 LT is that CSES-01 satellite has this time at the equator fixed for all of the world at night-time, so the obtained _TEC_ map will be easily comparable with the CSES-01 data. Furthermore, the global distribution of _TEC_ and Ne permits discrimination if the identified anomaly is a global phenomenon or local, with more chances to be produced by the volcano activity even if other proof is needed to demonstrate such a geophysical source. In the following figures, we show the days that are depicted with an outlier in electron density by satellite CSES-01 in Figure 23, and we resume the days represented and some notes in the following Table 11.  
In conclusion, by the comparison of _TEC_ data from GIM with in situ Ne observation made by CSES-01, a well and overall agreement was identified detecting the same ionosphere structures, including a peak in the Southern hemisphere between Australia and New Zealand on 26 August which was an unusual structure with respect to the other presented day. This confirms the scientific reliability of CSES Ne data, and furthermore, CSES provided very important measurements as it is made in situ and on the topside. In fact, the difference sometimes underlined by the comparison of _TEC_ and CSES Ne in the localization of the maximum could reflect a different vertical stratification of Ne, as the measure of CSES is punctual (in-situ) observation at about 510 km of altitude, while _TEC_ is more representative of a lower altitude, as the maximum concentration of electron density is located between 250 km and 400 km depending on the season, longitude, geomagnetic activity, and local time (here fixed), and it is known as hmF2 [99]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Figure** & **Day [2021]** & **Parameter** & **Notes** \\ \hline Figure 11 & & _TEC_ & TEC and CSES Ne are well in agreement. \\ Figure 12 & & _N_e (CSSES-01) & The high value of Ne over La Palma seems more a global disturbance. \\ \hline Figure 13 & & _TEC_ & Global distribution of _TEC_ and Ne from CSES present the same structures. The disturbance seems global. \\ Figure 14 & & _TEC_ & The structures in _TEC_ and CSES Ne are compatible, even if the localizations of maximum are different \\ \hline Figure 11 & & & \\ Figure 11 & & & \\ Figure 11 & 1 and 2 August & & The distributions of _TEC_ and CSES Ne are well in agreement. The enhancement above “La Palma” volcano seems a local anomaly. \\ Figure 11 & & & \\ Figure 11 & & & \\ \hline Figure 11 & 26 August & _TEC_ & Ionospheric structures are more complex and they are well depicted by both _TEC_ and CSES Ne satellite. Disturbance seems global phenomenon \\ \hline \hline \end{tabular}
\end{table} 
Table 11: List of the maps of Ne and _TEC_ that are compared in this appendix. Figure A5. TEC map of 2 July 2021 at 2 LT. Figure A8: CSES-Ne measurements of 7 July 2021 at about 2 LT. The bold black numbers represent the UT time of the centre of each shown track. Figure A11. TEC map of 1 August 2021 at 2 LT.  
Figure 14: CSES-01 Ne distribution of 2 August 2021. The bold black numbers represent the UT time of the centre of each shown track.