GPS Scintillations and TEC Variations in Association With a Polar Cap Arc

A unique example of a polar cap arc producing clear amplitude and phase scintillations in GPS L‐band signals is presented using observations from an all‐sky imager and a GPS receiver and a digital ionosonde at Resolute Bay and the SuperDARN Inuvik radar. During the southward interplanetary magnetic field (IMF) condition, 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 and 630.0 nm images. When it intersected the raypath 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 under the southward IMF condition were creating the scintillations. It provides evidence for the existence of polar cap arc scintillations that may be harmful for satellite applications even through L‐band signals. Plain Language Summary Polar cap arcs are the large‐scale aurora forms that stretch almost entirely across the polar cap and connect the dayside and night‐side aurora oval. It is a common phenomenon in the polar region, often appearing as a single or multiple arcs. Previous observations suggested that polar cap arcs are producing clear total electron content (TEC) enhancement within different scales in association with particle precipitations under various energy levels. However, the corresponding scintillations especially the amplitude scintillation is still under controversy, which are requiring the precise evidence to decide the scintillation effects. We present here for the first time a case study of polar cap arc under the unique IMF condition to investigating the corresponding scintillation effects and also the TEC variations. The results reveal that the polar cap arc can produce both amplitude scintillation and phase scintillation clearly and significant TEC variations. It is showing us a new insight on the polar cap arcs, reminding us pay attention to the harmful effects on satellite/navigation applications. Key Points We report a polar cap arc producing clear amplitude and phase scintillations on GPS L‐band signals with large total electron content (TEC) enhancements The polar cap arc moved at a horizontal speed of ∼700 m/s, as revealed by simultaneous ground‐based all‐sky 557.7 and 630.0 nm images Both scinti