A theoretical framework for understanding relationship between space weather indices and GPS ionospheric delay

Space weather effects, and the ionospheric disturbances in particular, have been identfied as the major single component of the GNSS error budget. For that reason, the research into the space weather ionospheric coupling has become the major cornerstone in the development of mitigation techniques for the space weather-induced GNSS vulnerabilities and risks. Here we present a theoretical framework, based on Appleton-Hartree formula and experimental models, that relates the space weather (solar and geomagnetic) indices to the GNSS ionospheric delay, thus establishing a theoretical framework for establishing relationship between the space weather observables and the major source of GNSS positioning error.