Trans-ionospheric signals using radio frequencies below 10 GHz propagate through the ionosphere and are influenced by refraction, diffraction and scattering of radio waves. These ionospheric effects are relevant for technical systems in the navigation domain, causing enlarged distance estimation between satellite and receiver. Well established ground-based GNSS measurements offer a unique chance to permanently monitor the electron density and its structure of the ionosphere- plasmasphere system in near real time. We will present a GNSS data processing system developed to characterize the actual and future state of the ionosphere. The system automatically processes and distributes high rate GNSS data (1Hz) of several hundred GNSS receivers from GNSS-reference networks worldwide.