Exploiting the Galileo High Accuracy Service Under Equatorial Ionospheric Scintillation

The Galileo High Accuracy Service (HAS) provides Precise Point Positioning (PPP) corrections potentially enabling decimeter level position accuracies. The rump-up of the Galileo HAS development is coinciding with the 25th solar cycle progression and the consequent solar activity increase. The current solar peak, which is forecast for 2025, will be much more intense than expected with events stronger than the ones occurred during the previous solar cycle. Solar activities may induce strong scintillation events on the received Global Navigation Satellite System (GNSS) signals. These may be particularly intense at the equatorial regions. Therefore, the equatorial scenario represents a challenge for high-accuracy users, such as the ones exploiting the Galileo HAS. This paper investigates the performance of the HAS service in the equatorial regions. For this purpose, data collected from low latitudes, in Presidente Prudente in Brazil, have been analyzed. The PPP engine implemented by the São Paulo State University (UNESP) has been used along with the Galileo HAS corrections to assess HAS performance during the occurrence of different levels of ionospheric scintillation. While severe scintillation can make position errors exceed the accuracy thresholds targeted by the HAS, a significant resilience to ionospheric disturbances has been observed for the service.