## 4 Discussion  
The findings presented in this study provide critical insights into the impact of characterising the ionospheric disturbances caused by the Beirut port explosion using multi-satellite observations. We analysed electron and ionospheric density data from three LEO satellites, Swarm-B, COSMIC-2, and DMSP-F17, that passed near the Beirut port explosion. The magnetic field and FAC data were examined using only Swarm-B. The IGRF-traced magnetic field lines clearly show that the ionospheric density disturbances were well-mapped between both hemispheres, as illustrated along the Swarm-B and DMSP-F17 paths in Figures 2 and 6, respectively. The endpoints of these traced magnetic field lines, corresponding to the observed electron density perturbations along the satellite trajectories, were located poleward of the Beirut port site (33.5\({}^{\circ}\)N). No ionospheric density disturbances were detected at the altitudes of the DMSP and Swarm satellites at latitudes lower than those of the Beirut port. However, unlike Swarm and DMSP, the COSMIC-2 RO profiles at UT = 15.5 h detected electron density perturbations at altitudes of 550 km, with two COSMIC trajectories positioned equatorward of the explosion site. The red and cyan solid lines in Figure 10b refer to the trajectories of the Swarm-B satellite and the blue solids refer to the DMSP satellites. The dashed green lines refer to the traced magnetic field lines between the ionospheric perturbation regions in both hemispheres. The universal time for each satellite trajectory is marked in the same colour. Notably, DMSP-F17 (UT = 16:30), in conjunction with ground-based IGS observatories,  
Figure 9: Traced International Geomagnetic Reference Field magnetic field lines (blue) connecting the Northern and Southern Hemispheres. The red lines represent the trajectories of the COSMIC satellites, while the magenta dot marks the location of the Beirut port explosion. Dot in magenta colour indicates the position of Beirut port. confirmed the detection of TIDs at 3000 km from Beirut [31]. Similarly, this study reports these ionospheric disturbances in conjunction with Swarm-B at the same location. However, Swarm-B passed more than two hours after the DMSP, and both satellites confirmed conjugate hemispheric ionosphere disturbances, indicating the persistence and large-scale nature of these perturbations. Unlike previous studies [28; 29; 31; 49], this study tracked this event for an extended period after the explosion. Ionospheric disturbances caused by the explosion, detected by DMSP-F17 1.5 h after the event over the mid-latitudes, were also observed by Swarm-B at the same location, but 3.75 h after the explosion. These late coincidence observations indicated long-lasting TIDs caused by the explosion. The absence of prolonged ringing signals in the hmF2 or foF2 data, as reported in [31], may be attributed to the use of low-time-resolution data (8 min). Overall, our results indicate that the ionospheric disturbances observed in this study exhibit clear hemispheric conjugacy, reinforcing previous assertions that such disturbances are often mirrored in both hemispheres due to interhemispheric coupling processes [14; 17; 29; 49]. It is worth noting that [31] discussed the reason for the absence of TIDs along the path of the DMSP south of Beirut in terms of low ion neutral collision at the high altitude (850 km) of the DMSP. The absence of equatorward ionospheric Ne disturbances at the low altitude of Swarm-B (520 km) provides additional insight into the altitude range in which Ne disturbances are absent along the satellite, as shown in Figure 10b.