Recombination and transport in the nighttimeFlayer of the ionosphere

A method by which the recombination coefficient of the nighttime F region of the ionosphere can be determined, previously applied to mean monthly Puerto Rico true height profiles, has been applied to results from six sounding stations at different latitudes. Further work has been done on the effect of various assumptions used in the analysis. No large latitude dependence of the recombination coefficient at 300 km was observed. A large seasonal effect was found, however. The analysis has been extended to the calculation of vertical diffusion and total transport velocities, and a determination of the diffusion coefficient effective in the nighttime F region was obtained. The diffusion coefficient was found to be for current models for the neutral atomic oxygen density. Vertical drift velocities determined from mean monthly profiles derived from hours for which Kρ was less than 4.5 were found to be generally lower than 10 m/sec.