## 8 Discussion
It can be noted that Ne disturbances in the daytime are rare and small at a wavelength of 300 km. It is possible that the strongly ionized ionosphere is less sensitive to seismic activity than the ionosphere during nighttime. It should be pointed out that the Ne vertical profiles also differ between day and night, and therefore, different parts of the Ne profile layers can be sensed by the LPs during days and nights. The very short 80 km wavelengths have shown some more sensitivity to seismic activity in the daytime, but the amplitudes of these irregularities are much smaller, and they correlate equally with seismicity and geomagnetic indices. The visual observation of the correlations in Figures 7-15 is summarized by the application of the PCC. The PCCs of nine 3-month data samples confirm the initial findings on the predominant correlation of the pair composed of the Swarm Ne PSD maxima and the cumulative sum of seismic energy. The PCC is calculated for 12 pairs of quantities in nine data samples, i.e., Swarm Ne PSD from the three Swarm satellites is compared to the cumulative sum of seismic energy described in Section 5, to the ap index, the Dst index, and F10.7. The calculation is repeated three times more for the data averaged by the moving median in 5-day, 7-day, and 10-day windows. The first nonaveraged calculation applied the seismic energy average within 5 days, as its calculation from a shorter sample of irregular earthquakes could provide too many gaps. The solar radio flux is kept in the original daily series form in all four calculations, as it exhibits, rather, long-term behavior, although a daily resolution. The PCC revealed good confirmation of the visual findings, particularly in the nighttime observations in Figures 7-11. The daytime observations have already been visually assessed in Figures 12-15 as more problematic or needing more insightful spectral analysis, and this is also confirmed by the PCC values. From the visual inspection of Figure 8, in turn, we did not expect an evident Swarm-seismicity correlation in Africa, where only single earthquake remains after applying the 5.0 magnitude threshold. However, Figure 8b shows that a large Ne disturbance occurred just before this single earthquake. Figure 16a can clearly confirm nighttime correlations in Papua New Guinea in the winter when PCC values for Swarm-seismicity pairs reach even 0.4-0.5 for Swarm A and C. The nonaveraged Swarm Ne PSDs only selectively indicate their better correlation with seismic energy in the summer, and only for Swarm B, but they are also surprisingly well correlated with seismicity for Swarm B in Africa. Figure 16b applies 5-day averages of Swarm Ne PSD, as well as the same averages of ap and Dst and the 5-day sum of seismic energy. The averaged Swarm Ne PSD is already visually assessed as being more representative in the LAIC when studying Figures 7-15 and this usefulness is confirmed by the PCC. The black PCC bars increase in the winter nighttime in Papua New Guinea and start to increase in the Aleutian Islands in Figure 16b, whereas the respective green and orange bars for geomagnetic indices remain low or negative. Figure 16c presents the PCCs of pairs of series that are averaged using a 7-day window (Swarm Ne PSD, ap, and Dst indices), the cumulative sum of seismic energy for 7 days, and the daily F10.7. The only pair for which the PCC noticeably increases is the Swarm-seismicity pair, the black bars of which reach at least 0.3-0.4 in the winter and summer in Papua New Guinea and in Aleutian Islands. The 10-day averages increase the black PCC bars even more to 0.4-0.7 for all nighttime datasets, except Swarm A and C in the African region. These values are much higher in comparison to other pairs of quantities, the PCC of which is negative or sometimes reach at most 0.2-0.3 in single cases. It should be added that high PCC values for daytime data and Swarm-seismicity pairs can be also found in Papua New Guinea in the spring and in the winter, but it is only observed for the Swarm Ne PSD sampled at 80 km wavelength.