GPS-based ionospheric tomography with constrained IRI as a regularization

Recent developments in ionosphere remote sensing, in particular techniques using the global positioning system (GPS) provide an unprecedented capability for monitoring the state of the ionosphere, its reaction to solar-terrestrial events as well as ionospheric wave phenomena. There have been many methods that were suggested to study the feasibility of using the International Reference Ionosphere (IRI) model as a regularization profile for ionospheric tomography experiments. Due to the limited-angle geometry, the vertical precision of ground-based GPS ionospheric tomography still needs to be improved to meet the requirements of some applications, such as monitoring the ionospheric distributions during the ionospheric storm periods. HmF2 (peak height of F2 layer of ionosphere) obtained by vertical soundings as a constrained parameter to IRI will improve the vertical resolution of the ground-base GPS ionospheric tomography. Vertical and oblique sounding data obtained from CRIRP while TEC data obtained from a meridional chain of 6 GPS satellite receivers located in China are used for reconstruction of the mid and low latitude ionosphere, maximum entropy regularization method was used to solve the discrete ill-posed problems, numerical simulations show that the constrained IRI has the potential of becoming a effective regularization profile for ground-based GPS ionospheric tomographic reconstruction of the ionosphere. It has also been observed that the foF2 values obtained from reconstructed images that use constrained IRI as a regularization profile are closer to measured values than those obtained from the images reconstructed with the original IRI regularization profile.