Results from Automated Ionospheric Data Analysis for Ground-Based Augmentation Systems (GBAS)

Extremely large ionospheric spatial gradients could cause potential integrity threats to Ground-Based Augmentation System (GBAS) users. The importance of understanding ionosphere behavior is not limited to cases of extreme ionospheric events. Broader knowledge of both nominal and anomalous ionospheric behavior would help improve the design and operation of GBAS. We developed an automated tool for long-term ionosphere monitoring to continuously monitor ionospheric behavior during the life cycle of GBAS. This paper presents the results obtained from processing ionospheric data using the automated tool. Pre-existing ionospheric storm data are processed to populate the current threat space with newly discovered ionospheric anomalies. Durations of ionospheric anomalies exceeding a threshold within a continuous arc are also investigated in this research. This tool also supplies broader statistical estimates of ionospheric behavior under all conditions. In this paper, we analyze day-to-day variations of typical ionospheric statistics observed from a dense GPS network. The results demonstrate that some correlation between the statistics and a geomagnetic index exists even on nominal days. The automated tool not only identifies gradients large enough to threaten GBAS users but also provides reliable ionospheric statistics.