Occurrence of Phase Fluctuations of GPS Signals in the High Latitude Ionosphere During Geomagnetic Storms

Dual-frequency measurements of the differential carrier phase of GPS L₁ (f₁,= 1.575 GHz) and L₂ (f₂ = 1.228 GHz) signals have been used to study the development of phase fluctuations at high-latitude ionosphere during geomagnetic disturbances. The ionosphere irregularities are responsible for scintillations and phase fluctuations of GPS signals. Because of the depressive nature of the ionosphere the dual-frequency GPS phase measurements provide information about variations of the ionospheric total electron content (TEC). The paper analyses the occurrence of strong phase fluctuations of GPS observed at Antarctic stations. The fluctuations caused large scales ionospheric irregularities which were associated with occurrence of polar patches in TEC. The peculiarities of the latitude-longitudinal development of GPS signals phase fluctuations are described.