GPS Loss of Lock Events and Ionospheric Turbulent Features: Decomposing Solar and Geomagnetic Activity, Interplanetary Features and Seasonal Dependencies

The ionospheric irregularities are variations in the plasma density with varying sizes ranging from a few meters to a few hundred kilometers, generated at different altitudes and latitudes. They may have adverse effects on the Global Navigation Satellite System (GNSS) being responsible for both the degradation of its positioning accuracy and the occurrence of signal losses of lock (LoL) during which GNSS receivers can no longer track the signal sent by the satellites. Nowadays, since many of the critical infrastructures on which our society depends are related to the proper operation of these systems, the study of plasma density irregularities plays an important role. Recently, it has been established that, among all possible ionospheric irregularities, only those in a turbulent state and characterized by high values of the Rate Of change of the electron Density Index (RODI) and a certain degree of intermittency, seem to be associated with the occurrence of LoL events.

With regard to this, in this study a detailed analysis is carried out using data recorded from July 15th, 2014 to December 31st, 2021 onboard two of the three satellites of the Swarm constellation. The high-latitude spatial distributions of this specific kind of ionospheric irregularities and of LoL events are reconstructed, highlighting at the same time their North-South asymmetry, along with their dependence on solar and geomagnetic activity, interplanetary features and season. The results of this work suggest that ionospheric irregularities in a turbulent state and characterized by high values of RODI can be used as a proxy to identify the regions where there are the physical conditions favorable to trigger LoL events.

The authors acknowledge financial support from Italian PNRA under contract PNRA18_00289-A "Space weather in Polar Ionosphere: the Role of Turbulence."