Tomography of the ionosphere with geostatistical inversion

The ionosphere is the upper part of the atmosphere where sufficient free electrons exist to affect the propagation of radio waves. Typically, the ionosphere extends from about 50 -1000 km and its morphology is mainly driven by solar radiation, particle precipitation and charge exchange. In the last decade Global Navigation Satellite Systems (GNSS, e.g. GPS and GLONASS) measurements have become one of the major tools for ionospheric sounding enabling the derivation of the total electron content (TEC) along a satellite to receiver ray path.

Our interest is the reconstruction of the ionosphere's electron density in order to mitigate the ionospheric delay in applications such as GNSS positioning and satellite-based radar imaging. Following the ionosphere's behaviour we establish a non-stationary spatial covariance model of the electron density, where its parameters are estimated in a maximum likelihood approach. Henceforth the integral GNSS TEC measurements and a non-stationary trend model are incorporated. Based on the derived spatial covariance the electron density is estimated by kriging with linear functionals.