LAUSR

Ionospheric tomography based on the observed total electron content along different satellite-receiver rays is a typically ill-posed inverse problem. Incorporating the electron density profiles data from COSMIC radio occultation technique and ground ionosondes, the Tikhonov regularization method is adopted to reconstruct the 3-D ionospheric electron density, and a regularization parameter is used to balance the weights between the prior (or background) information and real measurements. To determine the optimal regularization parameter, the model function in the modified L-curve method is used. This new method combines the advantages of the model function approach and L-curve criterion, and it has not only high accuracy, but also rapid convergence. To validate the effectiveness of this reconstruction algorithm, both the ideal test and real measurements test are carried out, and the results show that this algorithm can significantly improve the background model outputs.