Continuous electron density measurements up to 200 km

Abstract

Measurements in the ionosphere using the Seddon propagation technique were conducted with the Viking 10 rocket, launched at 10:00 a.m. MST on May 7, 1954, at the White Sands Proving Ground, New Mexico. This rocket reached a record altitude of 219 km, and provided very good data for both upward and downward trajectories. Ordinary and extraordinary indices of refraction at 7.754 Mc were measured in the region surrounding the rocket. From these indices, it was possible to determine accurately the electron distribution from 84 to 200 km. By using the P′-f records taken during the rocket flight, the electron density curve was extrapolated up to the maximum of the F2-region (2.9×105 el/cc at 288 km). The measurements showed a rapid increase in density from 1×104 el/cc at 91 km to 1×105 el/cc at 101 km. This was followed by additional but less rapid increases up to the peak of the F1-region (2.1×105 el/cc at 170 km). Densities in the 170- to 200-km region were, in general, five to ten per cent lower than the F1 maximum density. Although obtained during a period of low sunspot activity, these latest results agree remarkably well with previous results reported by Seddon and Jackson for periods near the sunspot maximum. In all cases, the daytime ionosphere was seen to remain dense throughout the E-region and up to the F-region, with only occasional minor peaks in density. In all cases, the distribution obtained agreed very closely with the P′-f records. Sporadic echoes are apparently due to partial reflections from high gradient regions.