Ionospheric tomography from a reference GPS/MET experiment through the IRI model

In earlier studies, we implemented the Multiplicative Algebraic Reconstruction Technique (MART) to reconstruct two-dimensional ionospheric structures from measured TECs through the receptions of the GPS-to-LEO signals and/or the NNSS-to-ground beacon signals. To examine the accuracy of the reconstructed image we need ground-based validation systems which are difficult to obtain. However, such comparative investigation is needed if one aims to improve tomography inverse techniques and algorithms. In this study, we propose a simulation scheme to carry out this task. We first simulate the GPS-to-LEO TEC measurements through the IRI model by integrating electron densities along the "straight" ray occultation paths between the GPS and LEO satellite obtained from the real GPS/MET experiment. Contiguous tomographic images are then derived by the MART algorithm within the "reference" GPS/MET experiment. They are verified by comparison with the "true" IRI-modelled ionosphere. We show that simulation/reference results can be used to find the optimal reconstruction strategy in space-based ionospheric tomography.