The Global Navigation Satellite System (GNSS) signals are easily affected by the ionospheric condition. Disrupted GNSS signals are highly refracted, and occasionally loss of signal locks occurs when the ionosphere is extremely disturbed. It is called as the ionospheric scintillation and it could make an error for timing and positioning using GNSS. The ionospheric scintillation appears on GNSS signals of amplitude or phase. Each scintillation event is indexed as S4 (normalized standard deviation of signal strength in a window) and σφ (standard deviation of phase in a window), respectively. The GNSS communication disruption at low latitude region caused by the ionospheric events has been widely investigated, while the study at high latitude region is relatively inactive due to difficulty of observations. However, research on the ionospheric scintillation at high latitudes is becoming increasingly important for such reasons as the use of airplane polar routes. Even though it is unveiled that high latitude scintillation on GNSS signals are related to auroral activity, it is still needed to study on the ionospheric scintillation at more higher latitude region such as inside of polar cap or near magnetic pole. Korea Polar Research Institute (KOPRI) and Korea Astronomy and Space Science Institute (KASI) have operated the ionospheric scintillation monitor at high latitude station in Antarctica, Jang Bogo Station (JBS; 74.62°S, 164.22°E), to observe an aspect of the ionospheric scintillation. JBS is magnetically located inside of polar cap region so that it is worthful to study the GNSS scintillation at magnetic high latitudes. We calculated occurrence rate of the ionospheric scintillation using the indices (S4, σφ) over JBS for 2 years (2017~2018) and statistically analyzed. Amplitude scintillation (S4) occurs only lower elevation angle below 30˚ which is not appropriate to be thought as the ionospheric effects, while phase scintillation (σφ) clearly shows not only the ionospheric effects at meaningful elevation angle but also dependences for azimuth angle, season, magnetic activity, magnetic local time (MLT) and signal frequency. It indicates that the usage of the GNSS communications at high latitudes should consider above various parameters. In this presentation, we will show the results and discuss the statistical characteristics of the ionospheric scintillation on GNSS signals and related mechanisms.

Keywords: ionosphere, scintillation, high-latitudes