# Retrospective Study on Seismic Ionospheric Anomalies Based on Five-Year Observations from CSES
## 3 Results
### An Example of EQ Case Analysis
The blue curves illustrate the ascending orbit (nightside) trajectories of the CSES-01 satellite. The black sector boundary is the boundary of an enlarged image. Figure 5: The disturbances in \(Ne\) and \(N_{O\bullet}\) over the influential area of the Türkkiye EQ from 11 January to 9 February. From the top panel to the bottom panel: The space weather indexes (\(Kp\) and \(Dst\)), \(Ne\), the change amplitude (%) of \(Ne\), \(N_{O\bullet}\), and the change amplitude (%) of \(N_{O\bullet}\). The red vertical lines in all panels mark the time of the EQ. In the first panel, the blue bars represent the \(Dst\) index, and the green curves correspond to the \(Kp\) index, while the red horizontal dashed lines represent the value of \(Kp=3\). In the second and fourth panels, the current variation trend of \(Ne\) and \(N_{O\bullet}\) is depicted as blue curves, while the background trends (i.e., median values) are represented by black curves; the upper and lower boundaries are shown as pink curves. In the third and fifth panels, the blue lines represent the change amplitude (%) of \(Ne\) and \(N_{O\bullet}\), and the red horizontal dashed lines represent the disturbance amplitude of 50% and \(-\)50% respectively. before and after the EQ. Figure 6 displays the difference maps of the magnetic field at the 70 Hz frequency from 11 January to 9 February 2023 around the Turkiye EQs. Panels (a) to (f) represent six revisiting orbit periods, spanning 25 days before and 5 days after the EQ, specifically 11-15 January, 16-20 January, 21-25 January, 26-30 January, 31 January-4 February, and 5-9 February. From the difference maps, it is evident that the Power Spectral Density (PSD) values of the magnetic field exhibited significant enhancement throughout the region during the period from 11 to 15 January (Figure 6a, 20 to 25 days prior to the mainshock) and from 5 to 9 February (Figure 6f, after the mainshock). Given that _Kp_ indexes exceeded 3 during these two periods, the obvious large-scale enhancements are more likely attributed to space weather, which did not appear during other time windows. Apart from these difference maps, a slight enhancement in the southwest of the epicenter (marked by a black arrow) under quiet space weather conditions could be observed in Figure 6e (31 January-4 February), potentially linked to the Turkiye EQ activity. It must be noted that the difference map often appears disturbed, making it challenging to derive reliable seismic information solely based on this method [22]. Figure 7 displays a comparison analysis of the energetic electron flux integration around the Turkiye EQ. Similar to Figure 6, panels (a)-(f) represent six revisiting orbit periods, encompassing 25 days before and 5 days after the EQ. Around 10 days before the EQ, an anomalous electron flux integration increase was observed roughly 700 km north of the epicenter (indicated by the red arrow in Figure 7d). Furthermore, five days before the EQ, another pronounced anomaly appeared around 400 km north of the epicenter (marked by the red arrow in Figure 7e). This seems to indicate that the anomaly appeared 10 days before the EQ, intensified as the EQ approached, and subsequently vanished after the EQ. Figure 6: The difference maps of the magnetic field at the 70 Hz frequency from 11 January to 9 February 2023 around the Turkiye EQ influential area. The epicenters are marked with stars. Figures (**a–f**) correspond to the periods of 11–15 January, 16–20 January, 21–25 January, 26–30 January, 31 January–4 February, and 5–9 February, respectively. The black arrow in (**e**) indicates anomalies that may be related to earthquakes. Based on the examination results of all payloads, we confirmed that anomalies associated with the T\(\ddot{\text{u}}\)rkiewicz earthquakes were observed by four separate payloads (i.e., LAP, PAP, SCM, and HEPP), all of which emerged within ten days before the mainshock.