## 3 Results
### Analysis of Ionospheric DVTEC Disturbances
#### 3.2.3 DVTEC Signal Period Analysis  
In order to analyze the periods present in the DVTEC signal and its amplitude spectrum, the C-Morlet 1.5 wavelet transform was applied to five RAMSAC stations strategically selected in relation to the storm cells. Figure 17 shows the chosen stations (AZUL, MZGA, PEBA, SRLP, and TERO), along with the DVTEC measurement paths of each satellite and the DVTEC peak-to-peak amplitudes during the entire study period (00:00 UTC-08:00 UTC). In the map on the right, lightning is plotted on a 0.2\({}^{\circ}\) by 0.2\({}^{\circ}\) grid, and the locations where the maximum current peaks were recorded are indicated by stars. Observing the map on the right, we can notice that stations MZGA, PEBA, and TERO present a predominantly longitudinal path of their satellites, while stations AZUL and SRLP show a mostly latitudinal path, especially after 03:00 UTC. Continuing with the analysis, we examine the DVTEC variation for the selected five stations on the days both without and with AEA (refer to Figure 18). For the day without AEA, we observed DVTEC fluctuations with high frequency (Figure 18) and peak-to-peak DVTEC amplitudes ranging from 0.16 TECU to 0.29 TECU (see Table 3). On the other hand, for the day with AEA, we found DVTEC fluctuations with both low and high frequencies (Figure 18) and higher peak-to-peak amplitudes ranging from 0.32 TECU to 0.93 TECU (Table 3). In addition, during the day with AEA, we observe that the stations tended to reach their maximum DVTEC variation between 03:00 UTC and 05:00 UTC. After that time, they tended to return to their nominal state. \begin{table}
\begin{tabular}{c c c} \hline \hline  & \multicolumn{2}{c}{**Peak-to-Peak DVTEC Amplitude (TECU)**} \\ \hline \multirow{2}{*}{**RAMSAC Stations**} & **Day without AEA** & \multirow{2}{*}{**Day with AEA**} \\  & **(Reference Day)** & \\ \hline AZUL & 0.16 & 0.32 \\ CHIM & 0.27 & 0.66 \\ CHOY & 0.31 & 0.87 \\ CORD & 0.20 & 0.53 \\ ESQU & 0.32 & 1.35 \\ MZGA & 0.26 & 0.93 \\ ORAN & 0.19 & 0.37 \\ PEBA & 0.29 & 0.91 \\ RIO2 & 0.18 & 0.63 \\ SAJA & 0.20 & 0.65 \\ SRLP & 0.23 & 0.53 \\ SVIC & 0.25 & 0.40 \\ TERO & 0.21 & 0.64 \\ UNSJ & 0.21 & 0.55 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Peak-to-peak DVTEC amplitude of the 14 RAMSAC stations, for the reference and storm day in the whole study period (00:00 UTC-08:00 UTC). Table created by author. Figure 17: Maps of the 5 RAMSAC stations. The map on the left corresponds to September 9 and the one on the right to 10 November 2018. With colored dots, the trajectory in time followed by satellites 1, 18, 22, 27, 104, 117, and 118 are plotted. In both maps, we represent with colored diamonds the peak-to-peak DVTEC amplitude values. On the 10 November map, lightning count is plotted on the 0.2\({}^{\circ}\) by 0.2\({}^{\circ}\) grid, and locations where the highest current peaks occurred for IntraCloud (IC) and Cloud-to-Ground (CG) discharges are indicated with stars. Figure 18: Temporal variations in the differential vertical total electron content (DVTEC) of the 5 RAMSAC stations on the (**a**) reference day and (**b**) AEA day. On the y-axis, the stations are located 1 TECU apart. A scale has been plotted in the figure for reference. * The AZUL station satellite (Figure 19) passes through the southeast storm. The maximum peak of variation is reached between about 03:50 UTC and 05:00 UTC, when it is passing through the area with the highest number of discharges;
* The satellite of the PEBA station (Figure 21) crosses the storm located in the central region. This occurs between 04:00 UTC and 05:00 UTC;
* The satellites of stations MZGA (Figure 20) and TERO (Figure 23) cross the area in the Andes Mountains. The maximum variations of MZGA and TERO occur between 03:00 UTC and 04:00 UTC and between 04:00 UTC and 05:00 UTC, respectively;
* The satellite of the SRLP station (Figure 22) crosses the Andes Mountains. In addition, we found the largest DVTEC variations when the satellite passed through the storm region.