## 4 Results
### Single Orbit Analysis  
The single orbit analysis is the first step to locate any perturbations recorded by satellites over the EQ influential zone. The physical values (i.e., the power spectral density or amplitude of the electromagnetic field, the density/temperature of plasma parameters, or the flux of energetic particles) recorded by those orbits passing over the EQ influential zone are processed separately as Level 3 data product. Figure 2 shows an example of the Level 3 data product routinely produced in the CSES scientific application center, which shows the electron density (Ne) and temperature (Te) recorded by orbit No. 13962_1 on 8 August, ten days before the 18 August 2020, M 7.0 Sumatra EQ (see Table 2). The red curves show the observations from the current \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**No.** & **Place** & **UTC** & **Latitude (\({}^{\circ}\))** & **Longitude** & **Magnitude** & **Depth (km)** & **The Possible** \\  & & & & (\({}^{\circ}\)) & **(M)** & **Depth (km)** & **Seismo-Ionospheric** \\  & & & & & & & **Perturbation** \\ \hline  
9 & \
\begin{tabular}{c} Sumatra \\ island, \\ Indonesia \\ \end{tabular} & 18 August 2020 22:29:21 & \(-\)4.31 & 101.15 & 7.0 & 10 &
\begin{tabular}{c} The electron density \\ significantly increased \\ 10 days before the \\ mainshock. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._The third panel shows the information of EQs that occurred along the current orbit trajectory within one month; the \(y\)-axis represents the direct distance between the epicenters and the satellite footpoint; the square, circle, and triangle denote the EQs that occurred before, during, and after the time of the current orbit, respectively; and the EQ magnitude indicates the size of the square, circle, and triangle. The red and green color gradient denote the specific time of EQs that occurred before and after the passing time of the satellite, respectively. The bottom-left figure shows the space weather index (Kp and Dst) within one month (before the date of the current orbit). The bottom-right global map shows the orbit project and the epicenter. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**No.** & **Place** & **UTC** & **Latitude (\({}^{\circ}\))** & **Longitude** & **Magnitude** & **Depth (km)** & **The Possible** & **Seismo-Ionospheric** \\ \hline
10 & & & & & & & & The electron density and the electromagnetic field in the ULF/ELF band & \\  & & & & & & & & observed a simultaneous increase 8 days before the mainshock. & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \hline
11 & & & & & & & & An abnormal ULF wave appeared 10 and 2 days before the mainshock. & \\  & & & & & & & & The infrared hyperspectral methane, OLR, aerosol, and other long-term observation data observed anomalies more than a month before the earthquake. & \\ \hline
12 & & & & & & & & The abnormal ULF waves of Alaska 2021 11:57:42 & 55.30 & \(-\)157.75 & 7.0 & 10 & The abnormal ULF emissions occurred 12 and 4 days before and on the mainshock day. & \\ \hline
13 & & & & & & & & The electromagnetic field intensity in the ULF/ELF band & \\  & & & & & & & & increased on 4 days, and one day before the mainshock. & \\  & & & & & & & & \\  & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._Alternatively, the orbits passing through the epicenter areas are plotted as scatter values of different physical values along the orbit traces, as Figure 2 of [PERSON] et al. [13], which shows the abnormal enhancement of the power spectral density values in the frequency range from 300 to 800 Hz of the magnetic field. Figure 2: The typical Level 3 data automatically produced in the CSES scientific application center, taking the example of electron density observation from orbit No. 13962-1 on 8 August, ten days before the 18 August 2020, M 7.0 Sumatra EQ.