Characteristics of Ionospheric Irregularities Using GNSS Scintillation Indices Measured at Jang Bogo Station, Antarctica (74.62°S, 164.22°E)

Abstract

The Global Navigation Satellite System (GNSS) signals are highly dependent on the ionospheric condition which is composed of electrons and ions generated by solar radiation and particle precipitation. The ionospheric plasma irregularities may cause scintillation of the GNSS signals, or even loss of signal locks, resulting in the reduction of positioning accuracy and timing precision. Degradation of signal amplitudes (phases) is called amplitude (phase) scintillation, and can be quantified with an index, S4 (σφ) which is defined as normalized standard deviation of signal strength (standard deviation of phase) in a specific time window. It has been known that the phase scintillation phenomenon is frequent at high latitudes, and is related mostly with fast plasma flows in the polar region or energetic particle precipitation in the auroral region. Statistical studies are needed to understand the characteristics of ionospheric (both phase and amplitude) scintillations at high latitudes. Here, we report analysis results of ionospheric scintillations measured at Jang Bogo Station (JBS; 74.62°S, 164.22°E), located the inside of polar cap region in Antarctica. The occurrence rates of the ionospheric scintillation over JBS are derived for full 2 years (2017~2018) in solar minimum condition. Occurrence rates of amplitude scintillations increase only at lower elevation angles (below 30 ), implying little pertinence to ionospheric origin. On the other hand, the occurrence rate of phase scintillations shows distinct dependences on azimuth angle, season, magnetic activity, magnetic local time (MLT) and signal frequencies. Our analysis results suggest that users of GNSS should consider these parameters to prepare for degradation of GNSS performances at high latitudes.