## 5 Swarm Ne Disturbances during Nighttime of the 2016-2017 Winter and M5+ Earthquakes
This sum of approximate earthquake energy, calculated within selected 5-, 7-, and 10-day windows, will from here be called the cumulative sum of seismic energy. The quantity that is calculated this way reveals more long-term variation in seismicity, and similarly to the moving average referred to as Swarm Ne PSD, it is drawn using bold lines of the same color as its input quantity, i.e., a black bold line (Figures 7-15). It is proportionally rescaled in Figures 7-15, except in Figure 9, where it is increased six times. Figures 7-15 in the following chapters include the labels with time windows of the Swarm track selections recalculated to both UTC and LOC. The first high peak of the Swarm Ne PSD of satellite A at the wavelength of 300 km in Figure 7a occurs before November 10, which is close to an earthquake with M = 5.9. Another high peak comes after a relatively calm week on the first day with an earthquake with M = 5.0 (November 27, see also Figure 4c). Next, high peaks repeat twice before December 8. The other strong signals occur on the days of major earthquakes and one day after them, i.e., on December 8-9 and December 17-18, which is illustrated by the spectrograms in Figure 4d-g. The five particular days, i.e., the day of the first M = 5.0 (November 27), the days of major earthquakes, and the days after them, are denoted with blue dots in Figure 7a (but so are the other days presented in Figure 4). This more clearly reveals that Swarm A disturbances at a 300 km wavelength increase at that time. The same days that Swarm C passes are marked with large dots in Figure 7c, and the behavior of variations in the Swarm Ne PSD follows a similar trend as in the case of Swarm A. These observations suggest that Swarm Ne PSD variations in Swarm A and Swarm C in the analyzed time are noticeably correlated with M \(\geq\) 5.0 seismic activity in the region of Papua New Guinea. The analogous Figure 7b for Swarm B also includes five blue dots indicating the first M = 5.0, two major earthquakes, and two days after the major earthquakes, as well as three dots denoting the remaining days from Figure 5. The Swarm Ne PSD of Swarm also increases here with respect to the neighboring small values, which confirms their correlation with seismicity. Nonetheless, not all Swarm B disturbances at large dots are the largest throughout the three-month period considered. The largest peaks for Swarm B, which are at the same time larger than all values observed here for the Swarm A/C pair, are observed on December 12 and January 8 (Figure 7b), the latter of which has the spectrogram in Figure 5h. This is an example spectrogram of a larger-scale ionospheric disturbance detected by Swarm B, and we should add that the spectrogram for December 12 is similar. The disturbances of this type exceed the area of the tectonic plate boundaries and dominate in Figure 7b over the signals suspected to be seismically triggered. The geomagnetic ap index reaches 4+ on January 8 but is small on December 14, and Dst also exhibits no variations. Thus, the geomagnetic origin of these large disturbances, like those in Figure 5h, is suspected but not confirmed. There are even no unconfirmed EPBs from the L2 IBI product in Figure 5h, and therefore, the analysis of such signals is open, with a strong indication of geomagnetic activity. The F10.7 in Figure 7 increases a few days before the first major earthquake on December 8, but also at the time for the third major earthquake on January 22. The first F10.7 increase occurring at the beginning of December coincides with repeating M \(\geq\) 5 earthquakes before the major earthquake on December 8 and also with an increase in disturbed Swarm signals (Figure 7a-c). However, on January 22, the increase in F10.7 is co-located with the major earthquake, rather than with the Swarm A/C disturbed signals (Figure 7a,c). Nevertheless, some moderate disturbance of the Swarm B signal can be detected there (Figure 7b).