Automatic calculation of electron density profiles from digital ionograms 2. True height inversion of topside ionograms with the profile-fitting method

An efficient electron density profile inversion algorithm is developed for use on automatically scaled digital topside ionograms. The profile-fitting method described here models the topside ionosphere with a single polynomial, a method particularly suited for autoscaled data because it is not too sensitive to a certain amount of scatter in the h′(f) data and it makes use of ordinary and extraordinary ray echoes. The program was applied to input data consisting of O and X trace segments obtained from automatic scaling of a number of digitized ISIS ionograms. It is shown that fully automatic calculation of the topside electron density profiles from digital topside ionograms can be performed in less than 10 s on a Cyber 71 computer.