Ionospheric/protonospheric electron content studies using ATS-6

Measurements of ionospheric and protonospheric contents obtained at Aberystwyth from observations of the ATS-6 satellite radio beacon are reported. The monthly median diurnal behavior shows protonospheric contributions of approximately 15 to 20% to the total content along the ray path by day, rising to a predawn maximum of 35% in summer and more than 40% in winter. The protonospheric results are shown to be typical of those expected from other European stations and differences from earlier American measurements are explained in terms of ionospheric interactions in the conjugate hemisphere. The temporal gradients of protonospheric content provide information on the net integrated ionospheric/protonospheric plasma fluxes and the results obtained indicate the importance of plasma exchange with both local and conjugate ionospheres