Evaluation of Abel Inversion Method Assisted By an Improved IRI Model

Abstract

AbstractThe most significant error of the radio occultation ionospheric retrieval is brought by the spherical symmetric assumption of electron density in Abel inversion. We developed an improved inversion method that attaches additional horizontal constraints based on a background model in Guo et al. (2015, https://doi.org/10.1016/j.jastp.2014.12.008) and found the effect of the method depends greatly on the accuracy of the background model. In this study, an improved ionospheric model, which applies radio occultation ‐based F2‐layer parameters and an adaptive topside model into the International Reference Ionosphere (IRI), is employed as a new choice of background model. The improved inversion is evaluated in several aspects in the middle‐ and low‐latitudinal regions during equinox season (from 19 March to 18 April in 2008 and 2012) and throughout the year. Results show that the artificial plasma caves underneath the equatorial ionization anomaly crests caused by Abel inversion is to some extent eliminated during the daytime, and the negative electron densities in the E layer are also reduced by the improved method. The comparison between Constellation Observing System for Meteorology, Ionosphere, and Climate events and colocated incoherent scatter radar (ISR)/ionosonde observations indicates comparable accuracy of both methods. Moreover, the Global Ionosphere Maps is introduced as true reference of the vertical total electron density content. The mean vertical total electron density content errors derived through the improved inversion method are less than that of Abel inversion in the global scope.