The GPS Scintillations and TEC Variations in Association with A Polar Cap Arc

<p>The first example of a polar cap arc producing clear amplitude and phase scintillations in the GPS L-band is presented using observations from an all-sky imager and a GPS receiver at Resolute Bay and the SuperDARN Inuvik radar. The polar cap arc moved quickly from the dusk-side to the midnight auroral oval at a speed of ~700 m/s, as revealed by all-sky 557.7 nm and 630.0 nm images. When it intersected the ray path of GPS signals, both amplitude and phase scintillations appeared, which is very different from previous results. Moreover, the scintillations were precisely determined through power spectral analysis. We propose that the strong total electron content (TEC) enhancement (~6 TECU) and flow shears in association with the polar cap arc were causing the scintillations. It provides instructive evidence for the existence of polar cap arc scintillations that may be harmful for satellite applications even through L-band signals.</p>

Solar cycle and seasonal variations of the GPS phase scintillation at high latitudes

We present the long-term statistics of the GPS phase scintillation in the polar region (70°–82° magnetic latitude) by using the GPS scintillation data from Ny-Ålesund for the period 2010–2017. Ny-Ålesund is ideally located to observe GPS scintillations modulated by the ionosphere cusp dynamics. The results show clear solar cycle and seasonal variations, with the GPS scintillation occurrence rate being much higher during solar maximum than during solar minimum. The seasonal variations show that scintillation occurrence rate is low during summer and high during winter. The highest scintillation occurrence rate is around magnetic noon except for December 2014 (solar maximum) when the nightside scintillation occurrence rate exceeds the dayside one. In summer, the dayside scintillation region is weak and there is a lack of scintillations in the nightside polar cap. The most intriguing features of the seasonal variations are local minima in the scintillation occurrence rate around winter solstices. They correspond to local minima in the F2 peak electron density. The dayside scintillation region migrates equatorward from summer to winter and retreats poleward from winter to summer repetitively in a magnetic latitude range of 74°–80°. This latitudinal movement is likely due to the motion of the cusp location due to the tilt of the Earth’s magnetic field and the impact of the sunlight.