Multifrequency Observation of High Latitude Scintillation: A Comparison With the Phase Screen Model

Using multifrequency global positioning system (GPS) measurements from the Canadian High Arctic Ionospheric Network (CHAIN), an assessment of the weak-scattering theory (phase screen model) of ionospheric scintillation at high latitudes is performed. Scintillation data collected by global navigation satellite system (GNSS) ionospheric scintillation and TEC monitor (GISTM) receivers of the CHAIN provide a good background for testing the phase screen theory given the weak nature of the scintillation amplitude. Sixty-four scintillation events are studied in items of their spectral characteristics and fluctuation levels. Both amplitude (S₄) and phase (σ_φ) scintillation indices, as well as the power spectral index, are determined at multiple carrier frequencies (L1 1575.42 MHz, L2 1227.60 MHz, and L5 1176.45 MHz). Using the weak scatter theory, we found that the average frequency dependence of S₄ is f^−1.27. This implies that ionospheric irregularity spectra are steeper compared to those obtained directly from the power spectral density of signal amplitude fluctuations. Our results suggest that the frequency scaling of amplitude scintillation fails to account for the ionospheric irregularities of the smallest scales. Otherwise, the multifrequency scrutiny of the signal amplitude spectrum rollover frequency and the signal phase variation index provides results that are in good agreement with the weak scatter theory.