Ionospheric Conductance Derived from Satellite Measurments: Limitations and Implications

Ionospheric Pedersen conductance ∑_P can be remotely measured using electric and perturbation magnetic fields measured above the high – latitude ionosphere, subject to assumptions of sheet – like current systems, quasi – static electric and magnetic fields, neglect of magnetic perturbations generated by Hall currents, and locally constant ∑_P (Sugiura et al., 1982). Using Swarm measurements, we see large variability and lower – than expected magnitudes at small scales, and dawn – dusk asymmetries in large scales of ∑_P upon comparison with existing models and results. To rectify the observed discrepancies, we revisit the underlying assumptions, provide root – cause analysis, and discuss the implications.