4:15 PM - 4:30 PM
[PEM14-10] Durations of ionospheric gradients and plasma bubbles as ionospheric threats to GBAS
Keywords:ionosphere, ionospheric threat model, plasma bubble, ionospheric gradient, GNSS, GBAS
Steep ionospheric delay gradients of which widths are several tens kilometers or less are one of the ionospheric threats in GBAS, because steep ionospheric gradients with small spatial scales may not be detected neither by GBAS ground stations nor by an airborne receiver when the gradient stands between the GBAS ground station and airplanes. From the viewpoint of GBAS operations, it is important to know how long such gradient events would last to predict the duration of GBAS operation outage. Therefore, clarifying durations of steep but small ionospheric gradients is important for GBAS operations. Though the duration of the ionospheric delay depletions associated with plasma bubbles have been studied extensively, the duration of the steep gradients have not been studied well.
In this paper, we extracted the steep ionospheric gradients caused by plasma bubbles from the ionospheric delay differences between some pairs of stations using the single-frequency-carrier-phase based and code-aided (SF-CBCA) technique  and GEONET data. Once the plasma bubbles candidates and the satellites which is affected by the ionospheric disturbances are selected, ionospheric delay variations of each receiver derived by dual-frequency measurements for estimation of the durations for each ionospheric gradient. The analyses of durations of steep ionospheric gradients which could be the threat for GBAS operations will be reported.
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