Space Weather Effects on the GPS Scintillation Levels Received From Radio Occultations

The relationship between the global characteristics of the ionospheric scintillation S4 index and the level of geomagnetic activity is investigated. The 4-year dataset covers the bottom of the declining phase of solar cycle 23 and is used to study the diurnal and seasonal variations of the space-based S4 measurements obtained from a large number of Global Navigation Satellite System (GNSS) Radio Occultation (RO) events. The statistical patterns observed are used as quiet-time baselines to investigate the effects of geomagnetic disturbances on the measured ionospheric scintillation levels at different locations. In addition, these characteristics are investigated for different longitude sectors. A ground-based Ionospheric Scintillation Monitor (ISM) is also employed to determine the relationship, if any, between the S4 index measured on the ground and the S4 index derived from GNSS RO in the Asian sector. The feasibility of utilising the RO S4 index as a proxy for the level of amplitude scintillation measured on the ground is also explored and discussed in the context of space weather-related GNSS scintillation prediction.