The negative ion concentration in the lower ionosphere

Abstract

The processes leading to the formation and destruction of negative ions in the upper atmosphere are considered in detail. Even if the former are improbably rapid, and the latter are improbably slow, the day time equilibrium concentration of negative ions in the D and E regions does not seem to be sufficiently high to be readily reconcilable with the dynamo theory of the L and S magnetic variations. Thus on calculating the transverse conductivity of E by the usual method it is found to be such that the magnitude of the L current can apparently only be explained if the local tidal motion is 6000 times greater than at ground level; and the most recent work on the interpretation of radio observations on the movements of the ionosphere is opposed to an amplification of this order. There seems also to be little doubt that the transverse conductivity of D is not as great as is demanded by the theory in its present form. The fade-out enhancement of the electron concentration in the lower ionosphere is briefly discussed. It is pointed out that the possibility that it arises from photo-detachment by Lyman (α) radiation from solar flares cannot be excluded.