GPS Scintillations and Losses of Signal Lock at High Latitudes During the 2015 St. Patrick's Day Storm.

We investigate the Global Positioning System (GPS) amplitude and phase scintillations during a severe geomagnetic storm on 17 March 2015. The auroral oval expanded significantly due to a strongly southward interplanetary magnetic field (Bz was −25 nT). When the auroral oval was over Skibotn in northern Norway, significant enhancements in total electron content (TEC) fluctuations, amplitude, and phase scintillation were observed. The strongest amplitude and phase scintillations were observed when a TEC blob propagated across the field of view. Strong amplitude and phase scintillations were observed near the edges of the TEC blob. The European Incoherent SCATter ultrahigh frequency radar observed significant enhancement of electron density (from 0.8 × 1011 to 1.6 × 1011 m−3) near the edge of the TEC blob in the F2 region, while the E region was only slightly enhanced. This indicates that the plasma processes and instability modes, which accounted for the strong GPS scintillations, should involve the F2 region ionosphere. We also analyzed the tracking performance of the GPS receiver during strong ionospheric scintillation condition. While the receiver maintained tracking of the GPS L1 signal, the strong amplitude scintillation resulted in a power fade up to 12 dB‐Hz. Losses of lock occurred in the GPS L2 band. Both the power fade and rapid phase fluctuation should contribute to losses of lock. Plain Language Summary: We study the disturbance of satellite navigation signals (Global Navigation Satellite Systems, GNSS) during a severe geomagnetic storm on 17 March 2015. Substantial changes in the ionosphere caused degraded performance of the GNSS service through degrading the signal quality and/or failed signal tracking. The study of the GNSS receiver tracking performance under strong ionospheric scintillations provides important guidelines for future research and development of mitigation techniques. Key Points: Significant GPS amplitude and phase scintillations were observed in association with a TEC blob in the polar ionosphereThe geomagnetic storm resulted in losses of lock in the GPS L2 band and a 12‐dB‐Hz signal power drop in the L1 bandIonospheric irregularities cause signal power fades and rapid phase fluctuations, which both contribute to losses of lock for GPS signals [ABSTRACT FROM AUTHOR]