A profile inversion method for vertical ionograms

Inversion of ionograms from vertical measurements is significant for studying the ionospheric structure and ionospheric wave propagation, and it has attracted widespread attention. The model method is a relatively common inversion method for vertical ionograms. In this paper, a model inversion algorithm based on the multivariate QP model (single quasi-parabolic ionospheric profile model) is proposed, which is different from the traditional QPS model (where the multiple quasi-parabolic segment ionospheric profile model uses quasi-parabolic or anti-parabolic models to represent E, valley, and F1 and F2 layers). In other words, the electron density height profile of each layer in the ionosphere is no longer described by a single QP model. Still, it is based on QP as the basic unit and characterized by a combination of multiple QP units, and the entire vertical ionospheric profile consists of a series of QP unit models. Moreover, in the case of the multivariate QP model, determining the parameters of each layer becomes more complex. This study provides a more straightforward method, which can determine the entire QP unit profile by selecting one of the three parameters of each unit QP. Based on this model, the inversion of vertical ionograms was achieved, and the effectiveness of the inversion algorithm was verified based on typical vertical ionogram data.