An investigation into the day-to-day occurrence of GPS scintillation events in the Australian longitude sector

Applications that heavily rely on trans-ionospheric radio signals are subjected to many space weather phenomena that can adversely affect their operations. Perhaps the most significant space weather phenomenon affecting GNSS in particular is the generation of ionospheric plasma irregularities (or plasma waves) at locations close to the magnetic equator during the night time. As the GNSS signals pass through the ionosphere, they are effectively diffracted by the ionospheric irregularities, causing random fluctuations in the measured amplitude and phase of the signal; i.e., amplitude and phase scintillation. These ionospheric irregularities are associated with large plasma depletions, called Equatorial Plasma Bubbles (EPBs) that develop during the night time near the magnetic equator. The physical mechanism that drives the generation of these EPBs is the generalised Rayleigh-Taylor instability. The seasonal/longitudinal occurrence climatology of the EPBs is well documented, following decades of ground-based and space-based remote sensing and in-situ observations. However, there are still significant questions as to what exactly controls the day-to-day EPB occurrence. In this study, a multi-instrument approach is used to investigate the mechanisms driving the generation of EPBs in the Australian longitude sector during the equinox months, when EPBs are typically rather common. The results are then discussed in the context of formulating a GNSS scintillation event prediction capability.