## 3 Results  
### Single-Orbit Analysis  
The physical data of PAP and LAP around the epicenters within \(\pm 10^{\circ}\) in longitude, a period of about 30 days before the main shocks, were selected to be arranged as a time sequence to check the apparent disturbance variations that may be induced by seismic activity. To keep the original abnormal information, the data used in the time series analysis was not smoothed or interpolated. As shown in Figure 1 and Table 1, the epicenter locations of the Loyalty Islands (Ms 7.1 EQ) and the southeast of the Loyalty Islands (Ms 6.9 EQ) are very close. The occurrence time interval is very short--only about 50 days. Therefore, we think that the EQ  
Figure 3: The range of orbital regions selected for data analysis is shown in the black dashed-bordered rectangle, taking the Ms 7.4 Indonesia EQ as an example. The red star represents the epicenter, and the blue lines are the ascending orbits of the CSES-01 during the period. Format of annotation information: mmdd-orbit number. preparation conditions are similar, allowing us to compare their common characteristics of pre-EQ ionospheric anomalies. In addition, the latitude distance between the Indonesia Ms 7.4 EQ and the Papua New Guinea Ms 7.1 EQ is only 5.5\({}^{\circ}\), while their occurrence time interval is within 15 days, so we also have ideal conditions to carry out a comparison of common features. It is worth noting in Figure 4 that the profile of orbit 2939_1 on 14 August 2018, 15 days before the Loyalty Island Ms 7.1 EQ, is different from other curves, with significant synchronous variation in the area \(\sim\)200-550 km northwest of the epicenter. The values of _Ne_ and _No_\({}^{+}\) increased (_Te_ decreased) evidently, and _Vz_, which is vertical ion drift velocity, and positive (negative) values indicate downward (upward), increased strongly along the path of ground-to-space simultaneously, exhibiting the consistency of the plasma multi-parameter anomaly characteristics. Based on those reported by previous studies, before the EQ, the _Ne_ and _Te_ in the ionosphere displayed a negative correlation change, and the relative variations of _Ne_ and _Ni_ at a height of \(\sim\)500 km were similar, being consistent with our observations. With the increase of _Ne_ and _Ni_, the coulombic and elastic collisions of electrons and ions increase, and thermal energy is converted into kinetic energy to compensate for the lost energy, resulting in the decrease of _Te_. Among them, the relative variation of _No_\({}^{+}\) and _Vz_ is more prominent, and the spatial range of the perturbation is \(\sim\)350 km. After leaving the EQ abnormal area, these parameters returned to their original state. Figure 5 presents the abnormal perturbation phenomenon recorded by orbit 3775_1 on 8 October 2018, 8 days before the southeast of Loyalty Islands Ms 6.9 EQ, which is very similar to the one shown in Figure 4. In the area just \(\sim\)100 km northwest of the epicenter, the _Te_, _Ne_, _No_\({}^{+}\), and _Vz_ data show evident synchronous variations. The regional extension of the perturbation was also very similar, covering about 350 km. The difference from Figure 4 is that the northward shift distance of the disturbed area is shortened by \(\sim\)100 km compared with the epicentral latitude, and the disturbance variations of the _Te_, _Ne_, _No_\({}^{+}\), and _Vz_ are more prominent. Among them, the intensity of _No_\({}^{+}\) in orbit 3775_1 is about five times higher than the one in orbit 2939_1. After investigation, we identified that the phenomenon could be due to the moderate magnetic storm that happened on 8 October, which led to the overall significant increase of _No_\({}^{+}\), while the order of magnitude of electron parameters did not change significantly. Despite this, the variation is spatially coincident  
Figure 4: The synchronous abnormal perturbations of _Te_, _Ne_, _No_\({}^{+}\), _Vz_, _Ex_, and _Ez_ of orbit 2939_1 occurred on 14 August 2018, 15 days before the Ms 7.1 Loyalty Islands EQ influential area.