## 5 Discussion  
The CSES satellite has been ongoing for more than 6 years since it was launched in 2018 in China. More and more studies have reported on its achievements in data assessment and availability [37; 38; 39; 40], global geomagnetic field modeling [40], investigations of ionospheric events like magnetic storms [40; 41; 42], and ionospheric structures [25; 26]. However, one significant goal of the development of this satellite to monitor seismic activities around the world is always the main topic. Investigations of seismogenic influences on the ionosphere have absorbed more and more attentions either in earthquake case studies or statistical analyses of a large amount of events [23; 24; 27; 35; 43; 44; 45] to enhance our understanding of the topside ionospheric physics from lithospheric events. At the same time, the CSES satellite plasma data have tentatively been put into earthquake prediction practice since 2020 [24]. The contouring line method was first  
Figure 11: Fluctuations in the O\({}^{+}\) density recorded by the CSES satellite on night revisiting orbits (**a**) 33403 on 8 February, (**b**) 33479 on 13 February, (**c**) 33555 on 18 February, and (**d**) 33631 on 23 February 2024.  
utilized within the China area to process the original electron and ion densities and highlight possible precursory information associated with impending strong seismic activities. Two outstanding examples have been reported by [PERSON] et al. [24] in this period, and enhanced ionospheric fluctuations were successfully observed 14 days prior to the Maduo \(M_{\rm S}\) 7.4 earthquake and 11 and 6 days to the Menyuan \(M_{\rm S}\) 6.9 event in Northwest China. However, the contouring method is unable to reveal completely all ionospheric anomalies with different amplitudes. To deal with this problem, the automatic detection method developed by [PERSON] et al. [20; 21; 22] to statistically investigate the seismo-ionospheric influence has been alternatively introduced to search for probable ionospheric precursors weekly during earthquake prediction practice in China after the Wushi \(M_{\rm S}\) 7.1 earthquake on 23 January 2024. Ionospheric perturbations had been successfully detected two times in the following month near the Wushi aftershock area. A night electron disturbance was detected first at 2:00 local time on 24 January 2024 (a relative specified local time was 14:00 during the day and 2:00 at right for the CSES satellite), the next day after the Wushi main shock, with an amplitude of 38.3%. But no ion perturbations were searched at the same up-going orbit 33175. Meanwhile, obvious corresponding variations were also registered for other plasma parameters, like the electron temperature and O\({}^{+}\) and He\({}^{+}\) densities, when we examined their processed pictures (see Figures 4a and 5). However, the Kp index showed that these irregularities occurred in a moderately geomagnetically disturbed period (Figure 6), which can induce positive and negative fluctuations in the ionosphere [42; 46]. To confirm the influence of the solar activity on the ionosphere, the geomagnetic H component and geoelectric EW component measured at the nearest ground-based Hongqian station to the detected orbit had been checked and apparent perturbations (Figure 7) were found during 23 and 24 January, which seems to indicate that the ionospheric variations this time probably originated from solar activities and had no near relationship with the following Wushi aftershocks. However, it is well known that the influence of geomagnetic storm on the ionosphere is global [9; 25; 26; 42; 46]. Now, one question arises: why did these plasma bubbles occur only on this night at the 33175 orbit but not at other near orbits? It is well known that equatorial plasma bubbles (EPBs) are one of the typical ionospheric irregularities ranging from a few meters to hundreds of kilometers during nighttime at low latitudes and equatorial regions [47; 48; 49]. The EPBs are usually attributed to geomagnetic storms.