## 4 Discussion
Regardless, the space-based data showed no southward ionospheric disturbances, and ground-based studies [25; 29] have reported southward disturbances related to the explosion event around  
Figure 10: (**a**) The ionospheric ion density observed by the Defence Meteorological Satellite Program (DMSP-F17) satellite, (**b**) the electron density observed by the Swarm-B Satellite, (**c**) the field-aligned current data observed by the Swarm-B satellite, (**d**) the residual magnetic field components recorded by the Swarm-B satellite, and (**e**) a geographic showing the trajectory of the satellites DMSP and Swarm-B in red and blue solid lines respectively, while its traced magnetic field lines correspond to the north or south disturbances are shown in dashed lines. The green solid line is the traced International Geomagnetic Reference Field line for the two COSMIC trajectories. Dot in magenta colour indicates the position of Beirut port. UT = 15.4 h. Therefore, the lack of equatorward Ne ionospheric disturbances at the altitudes of Swarm-B and DMSP-F17 warrants further investigation using different datasets. The analysis of the FAC and magnetic field data from Swarm-B revealed distinct equatorward disturbances along path #3 (Figure 10c,d), observed both south of Beirut and in the conjugate Southern Hemisphere (elliptical green dashed lines). Despite the large amplitudes in both conjugate regions, as indicated by the dashed ellipses in Figure 10c,d, we could not confirm that these oscillations were directly related to the explosion. The passage of the satellite at dusk (19:45 LT) coincided with a significant hemispheric potential difference, naturally enhancing the FAC [33]. However, the local time conditions limited our ability to confirm whether the equatorward FAC and magnetic field ionospheric disturbances were related to the Beirut port explosion. Incorporating additional observational techniques would be valuable to provide further evidence or support any previously raised assumptions. The COSMIC technique investigates the altitudinal profile of ionospheric electron density, whereas the Swarm and DMSP techniques record in situ observations [34; 50; 51]. Southward, equatorial, and conjugate ionospheric disturbances observed by COSMIC were recorded at higher altitudes (>500 km) at different intervals from the explosion time. The IGRF confirmed that the disturbance observed in the Southern Hemisphere was mapped magnetically to its conjugate disturbed region in the Northern Hemisphere, as shown in Figure 9. Figure 11 presents the COSMIC profile locations and the rate of electron density change (\(dN_{e}/dt\)), illustrating significant ionospheric fluctuations at altitudes > 500 km. The red lines in Figure 11a,b represent the trajectory and variations in the ionospheric electron density at UT = 15.5 h, which were observed at the conjugate point in the Southern Hemisphere. However, the COSMIC trajectory over the equator at the same time did not simultaneously detect the ionospheric disturbances. The lower panels show the trajectory of the COSMIC satellite at UT = 18.1 h, when ionospheric disturbances were later observed over the magnetic equator (10\({}^{\circ}\)N). The observational patterns over the magnetic equator, where nothing was observed in DMSP and Swarm, but some signatures were captured by COSMIC RO, were generally consistent with the TID scenario presented by [31]. The low collisionality at the ionospheric topside altitude caused the TID wavefront to be highly field-aligned, and the horizontal magnetic field at the magnetic equator oriented the TID wavefronts almost horizontally flat. DMSP and Swarm (sampling the ionospheric density at a constant altitude along their respective orbits) did not detect these fluctuations. In contrast, the COSMIC RO measurements were able to capture these fluctuations because the altitude of the tangent point shifted over time during each RO event (i.e., there was an effective altitudinal scan).