Worldwide Ionospheric Data with Ionosonde

Ionospheric observations have been carried out in Japan since 1930s by
means of vertical sounding using ionosondes. The ionosonde produces
ionograms, which are recorded digitally on computer storage medium as
well as graphically on 35mm photografic film. The digitally-recorded
ionograms are collected from each stations with ISDN network and
reduced to numerical values and Summary Plots by the automatic
processing system at present. The ionograms obtained at Kokubunji are
manually scaled as well by experienced specialists to supplement
automatically scaled parameters.