Radio tomography of the ionosphere: Analysisof an underdetermined, ill-posed inverse problem, and regional application

摘要

After analysing the forward and inverse problems of radio tomography, a time varying three-dimensional imaging method of the ionosphere from GPS slant TEC data is described and applied at regional scale. Our approach is based on local basis parametrisation of electron density, and constrained by NeQuick ionosphere model and its spatial gradients. Our inversion scheme is fundamentally different from the data assimilation approach because it is not based on a physical ionosphere model. Preliminary results obtained with European GPS receiver data validate the stability of our method which is able to retrieve small-scale ionosphere features in properly resolved volumes. Many improvements are still possible on the algorithm, and a careful validation of inverted models by independent data is still necessary. However, our inversion algorithm is shown to improve the determination of the small-scale features of a coarse a priori ionosphere model.