# Perpendicular Electrical Conductivity in the Topside Ionosphere Derived from Swarm Measurements
## 5 Summary and Conclusions  
This study has, for the first time, characterised the electrical conductivity perpendicular to the geomagnetic field in the topside ionosphere through in situ measurements. The analysis was conducted using data from the Swarm A satellite, calculating the Pedersen and Hall conductivities according to Equations (15) and (16). The motivations behind this study are manifold. Firstly, the study allows us to extend and complete information from previous studies. In the works of [PERSON] et al. [55; 56; 57] parallel electrical conductivity has been extensively studied by using up to six years of in situ measurements in the topside ionosphere acquired by Swarm A and CSES-01 [58] missions. Here, a characterisation of the perpendicular conductivity is carried out. Parallel and perpendicular conductivities are, indeed, crucial for obtaining the conductivity tensor. The key findings underscore the significant role of solar activity and seasonal variations in modulating both Pedersen and Hall conductivities across different latitudinal regions. In the equatorial region, particularly within the F-region at Swarm altitudes, our results highlight the intricate dynamics influencing the EIA. The vertical plasma drifts induced by the daytime eastward electric field and the Earth's magnetic field generate peaks in electron density. These drifts are modulated by the Hall and Pedersen conductivities. During periods of high solar activity, increased ionisation enhances Pedersen conductivity, leading to more pronounced EIA peaks. Seasonal changes further impact these conductivities, altering the effectiveness of plasma drifts and the resultant ionisation distribution. Our climatological distributions, aligned with theoretical expectations, illustrate the distinct behaviours of conductivities parallel and perpendicular to the magnetic field. The parallel conductivity, dominant due to minimal collisions along magnetic field lines, contrasts sharply with the perpendicular conductivities, where Pedersen conductivity exceeds Hall conductivity. These findings validate our methodological approach and provide a robust framework for understanding ionospheric conductivity variations. Implications of these results extend beyond academic interest. The detailed conductivity maps and their seasonal and solar activity-dependent variations offer valuable insights for improving ionospheric models, which are crucial for applications in Space Weather forecasting and satellite communication systems. The ability to predict changes in ionospheric conductivity can enhance the accuracy of GPS and other satellite-based navigation systems, mitigate the effects of Space Weather on technological infrastructure, and inform the development of more resilient communication networks. In conclusion, this study enhances our understanding of ionospheric conductivities by examining the interactions between solar activity, seasonal variations, and ionospheric dynamics. The results align with the theoretical models used and identify specific patterns and anomalies at Swarm altitudes, particularly concerning Pedersen and Hall conductivities. These insights are valuable for improving Space Weather forecasting and satellite communication systems. However, the use of data from a single altitude (around 450 km) limits the generalizability of the findings across different altitudes, which is essential for a comprehensive understanding of ionospheric electrodynamics. Future research should focus on incorporating multi-altitude data to provide a more complete picture of ionospheric current systems and their interaction with geomagnetic field lines. Additionally, future studies should aim to characterise the Cowling conductivity, which is influenced by the Pedersen and Hall conductivities analyzed in this study. Another objective will be to reconstruct the current density distribution in the topside ionosphere at Swarm altitudes, using the tensor relationship outlined in Equation (2).