The variability of low-latitude ionospheric amplitude and phase scintillation detected by a triple-frequency GPS receiver

Ionospheric scintillation is a manifestation of space weather effects that seriously affect the performance and availability of space-based navigation and communication systems. This paper presents results from an investigation on the characteristics of the phase and amplitude scintillation of Global Positioning System signals at the L1, L2C, and L5 frequencies. Field data obtained by a scintillation monitor installed in São José dos Campos (23.1°S, 45.8°W; dip latitude 17.3°S, declination 21.4°W), Brazil, a station located near the southern crest of the equatorial ionization anomaly, were used for this purpose. The analyzed data were collected during 150 nights from November 2014 to March 2015, an epoch of moderate solar activity close to the recent solar maximum. Only measurements corresponding to an elevation mask of 30° and values above standard threshold levels were used in the analysis. Outstanding characteristics of amplitude and phase scintillation are analyzed and compared in this study. The different characteristics of the scintillation focused in this study include (1) the statistics of their occurrences at the three frequencies; (2) the local time distributions of the amplitude and phase scintillation at different intensity levels; (3) azimuth-elevation (spatial) distributions at different levels of the standard deviation of phase fluctuations; (4) scintillation enhancement and loss of phase lock conditions due to field-aligned (longitudinal) propagation; (5) the relationship between amplitude and phase scintillation parameters for the L1, L2C, and L5 frequencies; and (6) the frequency dependence of the amplitude and phase scintillations. Important results on these different characteristics are presented and discussed, and some outstanding problems for future investigations are suggested.