On the latitude-dependence of the GPS phase variation index in the polar region

It has long been established that the presence of irregularities in the ionosphere affects the propagation of radio waves, and in particular radio waves transmitted by GNSS satellites. Ionospheric scintillation is an important physical characteristic of radio wave signals propagating through the ionosphere. It is believed that a reverse backscattering analysis of the scintillating signals measured by GPS receivers on the ground may unveil some knowledge about the ionospheric irregularity structures causing the scattering in the first place and may in turn help understand the physical mechanisms causing the development of these irregularities. The Canadian High Arctic Ionospheric Network (CHAIN) GPS data are used to build probability functions for the phase variation index, which are best fit by the four-parameter Landau distribution. The fits reveal that the distribution scale-parameter value captures the known patterns observed in the phase activity. In particular, the seasonal and the solar cycle dependence are identified. On a yearly basis, the obtained scale parameter is linearly dependent upon the solar radio flux index F10.7. The same parameter increases with the magnetic latitude and reaches a maximum at the cusp region. These results pinpoints the cusp region as a major place where ionospheric structures affecting the radio signal phase are formed before they propagate poleward and equatorward. Furthermore and using particle scattering by a random medium, the distribution scale parameter obtained for σ Φ might be considered as the analog of the Total Electron Content. These preliminary results suggest that a detailed analysis of distribution of fluctuations in the radio signal can potentially provide a simple approach to develop scintillation climatological models.