Longitudinal variations of the electron concentration in the ionosphericD region

[1] Analysis of the longitudinal effects in the lower ionosphere revealed from the measurements by rockets and partial reflection method is presented. It is shown that in the summer and equinox periods the electron concentration in the altitude range 70–85 km at fixed zenith angle varies by a factor of 1.5–5.6 at the transition from the Pacific longitudinal sector to the Eurasian and American sectors. The longitudinal effects depend on season and time of the day: they are weak in the American sector and strong in the Eurasian sector. A conclusion is drawn that to reconstruct the longitudinal features of the global structure of the lower ionosphere, it is reasonable to attract the data obtained by the A1 method.