A stable and fast method of ionospheric tomography by using diverse data sources

The computerized ionospheric tomography (CIT) is an under-determined, ill-posed inverse problem. The limited-angle geometry and sparse receivers cause incomplete information in measurements, which limit the precision of the CIT imaging, especially in the vertical dimension. This paper puts forward a new method by combining vertical and oblique sounding data with the total electron content (TEC) retrieved from an assumed tri-band beacon of a planned Chinese satellite for seismological studies transmitting VHF, UHF and L-band frequencies. In this paper the bottomside of the initial profile for the iteration is specified by actual vertical while oblique sounding data and the topside specified by the Chapman layer model. This combined initial deviates from the actual electron density distribution and is smaller than those calculated only from the models. The appropriate initial will ensure that the iterative algorithm is reliable and steady. The numerical simulations show that electron density images reconstructed from only TEC using the three-frequency technique are significantly improved after combining real observation data of the ground-based vertical and oblique sounding. The results shown in this paper throw a new light on the application and potential of the solid network of a satellite beacon and ground-based facilities. (C) 2013 Elsevier Ltd. All rights reserved.