## 5 Conclusions  
This study identified the conjugate ionospheric disturbances linked to the 2020 Beirut port explosion (4 August 2020, at 15:08 UT) using multisatellite data. Analysis of the ionospheric electron density, magnetic field, and FAC data from (Swarm-B, DMSP, and COSMIC-2) satellites near the explosion site and its conjugate points revealed significant findings, highlighting the value of coordinated satellite missions in space weather research. Electron density perturbations were observed along the trajectories of DMSP (16:30 UT) and Swarm-B (18:57 UT) at locations far poleward from the explosion site in the Northern Hemisphere and at its conjugate regions in the Southern Hemisphere. The traced magnetic field lines confirm that the latitudes of these perturbations in both hemispheres are magnetically connected. Moreover, the wavelet spectrum revealed that the electron densities in the conjugate regions shared the same features in the frequency domain. However, Swarm and DMSP-F17 passed near the explosion site approximately 3 h and 1.5 h later, respectively; the prolonged and sequential observation of both satellites suggests the inertia of the ion  
Figure 12: (**a**) The residual electron density data (Ne) from both DMSP and Swarm, shown in red and blue, respectively. (**b**) The wavelet transformation of Swarm-B Ne. (**c**) The wavelet transformation of DMSP Ne. sphere. In addition, COSMIC-2 (15:33 UT) detected electron density perturbations in the topside ionosphere (>550 km altitude) at two conjugate points (30\({}^{\circ}\)N and 22\({}^{\circ}\)S). Three hours after the explosion (18:6 UT), COSMIC also detected ionospheric electron disturbances closer to the magnetic equator, suggesting the role of the TID travelling radially. Swarm-B's magnetic field and FAC data showed perturbations near the explosion, extending both equatorward and poleward, as well as in the conjugate Southern Hemisphere. However, attributing these variations solely to the explosion is inconclusive, as Swarm-B's dusk-time passage coincides with the natural FAC dynamics influenced by ionospheric conductivity gradients and large-scale hemispheric potential differences. These factors complicate the direct association between FAC perturbations and the explosion. This study provides strong evidence for conjugate hemispheric perturbations linked to the Beirut port explosion. These perturbations were identified through multiple observational datasets and traced in both hemispheres using a magnetic field line modelled using the IGRF model. However, the absence of equatorward conjugate perturbations in the electron density at the altitudes of the Swarm and DMSP trajectories warrants further investigation in future studies. Therefore, further analysis is recommended to investigate whether the equatorward ionospheric disturbances after the explosion are related to the TIDs or other mechanisms and to investigate whether the conjugate ionospheric disturbances are related to the electrostatic polarisation ionospheric electric field perpendicular to the TID wavefront or to the electromagnetic coupling process. Supplementary material associated with this article can be found in the online version at: [[https://www.mdpi.com/article/10.3390/rs1711908/s1](https://www.mdpi.com/article/10.3390/rs1711908/s1)]([https://www.mdpi.com/article/10.3390/rs1711908/s1](https://www.mdpi.com/article/10.3390/rs1711908/s1)), Figure S1: Projection of COSMIC satellite ionospheric profiles between 15:00-16:00 UT over the (a) Northern Hemisphere and (b) Southern Hemisphere. The red and blue indicate the COSMIC ion profile locations of the quiet day and event explosion. Panels (c) and (d) show quiet-time COSMIC profiles on 10 August 2020 and 9 August 2020, respectively. Panels (e) and (f) display the disturbed profiles recorded on 4 August 2020, in the Northern (e) and Southern (f) Hemispheres; Figure S2: Projection of COSMIC satellite ionospheric profiles between 14:00-16:00 UT on 4 August 2020, over the (a) Northern Hemisphere and (b) Southern Hemisphere.