The ion distribution above the F2maximum

Abstract

Observations of the ion distribution in the ionosphere indicate that the distribution up to 550 km is controlled in part by changes in the recombination rate with altitude, although diffusion exerts an increasingly important influence above the F2 maximum. It is further concluded that the ion distribution above 550 km is controlled by diffusion and not by recombination, although a further reduction in recombination rate with increasing altitude does occur. Charge-exchange reactions between oxygen ions and hydrogen atoms at an altitude near the base of the exosphere provide a source of thermal protons which move upward along the magnetic field lines together with an equal number of electrons and produce a medium for the propagation of radio whistlers. The computed distribution of protons and electrons is in reasonable agreement with whistler observations. The whistler medium is of telluric origin, and the source of ionization is the same as that for the F region. It is suggested that the region above 1800 km in which protons predominate over all other ions be called the protonosphere, to distinguish it from the lower ionized region normally referred to as the ionosphere.