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

b
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 F 2 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.