On the location of the ionospheric current systems responsible for the lunar and solar magnetic variations

From a study of the sunspot cycle influence on the lunar (L) and solar (S) daily geomagnetic variations, Malin, Cecere & Palumbo have suggested that the electric currents responsible for these variations do not flow in the E-region as has hitherto been accepted. Indeed they suggested that the L current may even flow in the F2 region. The consequences of such a suggestion are considered and it is shown that an L current in the F-region is highly unlikely from the dynamical point of view. The evidence for E-region currents is presented and it is suggested that the variation of E-region electron density used by Malin et al. to indicate conductivity changes in that region may not be a reliable indicator of such changes.