Experimental derivation of effective recombination coefficients in the lower ionosphere

The time lag of the diurnal electron density variation at D-region heights with respect to the diurnal ionization rate variation (assumed to be symmetric) is determined from empirical electron density profiles and from observed diurnal phase-height variation, and is interpreted in terms of effective recombination coefficients. Comparison with a model calculation of D-region ion composition (cluster ion to normal ion ratio) shows that this interpretation may be justified.