Geometric mean algebraic reconstruction technique : a tool for ionospheric tomography using GNSS receiver system

Abstract

ABSTRACT Ionospheric tomography is a widely utilized technique for investigating the electron density distribution in the ionosphere. This approach primarily relies on multiple line-of-sight total electron content (TEC) measurements from receivers positioned across the region of interest. In this study, we present a comprehensive methodology for formulating linear equations corresponding to each observation, simplifying them into a matrix form, and subsequently solving them using an iterative technique. To determine the electron density distribution, we have developed a modified version of the algebraic reconstruction technique (ART), termed the geometric mean algebraic reconstruction technique (GMART), to reconstruct the 3D electron density structure of the local ionosphere. The performance of GMART is evaluated against ART and the multiplicative algebraic reconstruction technique (MART) with a comparative analysis of the convergence behaviour of these iterative methods. The resulting tomographic images offer an extensive view of the ionospheric structure, facilitating the monitoring of spatial variations over time. The altitude profiles of the ionosphere derived from the GMART technique are further validated against ground-based ionosonde observations of bottom-side electron density profiles. The comparison reveals a strong agreement between the reconstructed electron density profiles and real ionospheric electron density measurements obtained from ionosondes.