Considering the limitations of current single pixel-based and function-based computerized ionospheric tomography (CIT) models, this paper proposes a new tomography model – COMBI, which combines these two models. COMBI model is able to reconstruct the three dimensional distribution of electron density with fewer parameters, and easy to compute, as well as very convenient to use. Through experime...

Recent developments in tomographic imaging allow the use of GPS satellite data to image the Earth’s ionosphere. Ground-based GPS receivers monitor the Earth’s ionosphere continuously and a comprehensive database of ionospheric measurements suitable for tomographic processing now exists. The tomographic inversion of these GPS data in a three-dimensional time-dependent inversion algorithm can rev...

One can divide the existing ionospheric methods for SBAS in two categories: tomography and methods relying on the thin shell model. At first sight, tomography appears to be the right choice. Tomography reconstructs the three dimensional density of the ionosphere from the available measurements. However, there are several drawbacks to tomography: the system of equations to be solved is often und...

The ionosphere is about 60-1000 km above the earth’s surface, which is actually plasma of ionized gas of the upper atmosphere by solar radiation and high-energy particles from the Sun. The ionized electrons concentrations change with height above earth’s surface, location, time of the day, season, and amount of solar activity. The total electron content (TEC) and electron density profiles are t...