Development of an ionospheric electron density assimilation model based on vertical sounding ionograms

Abstract Traditional assimilation models typically employ electron density profiles obtained through ionograms inversion as assimilation data, but due to the limitations of the inversion algorithm itself, these data deviate from the real electron density profiles, and their direct use introduces errors into the assimilation system. To minimize the errors generated during the processing of observational data, this study proposes to use the original ionogram as the direct observational data and the International Reference Ionosphere (IRI) model as the background field, and to realize the gradual fusion of the ionogram data and the background model through the Kalman filter algorithm. Meanwhile, this study introduces the adaptive grid delineation technique, which dynamically adjusts the grid size according to the characteristics of different height regions of the ionosphere, and realizes the refined modeling of electron density. Experimental validation shows that the assimilation effect of the method is remarkable: the consistency between the synthetic traces of electron density and the measured data is significantly improved, especially in the interlayer transition region of the ionosphere, where the electron density gradient changes significantly, and the description accuracy obtains a significant improvement.