High latitude ionospheric scintillations

The statistical characteristics of ionospheric irregularities are often described by specifying one or two of the statistical parameters of the scintillations that the irregularities produce in satellite radio signals. The most commonly used parameter for this purpose is the spectral index (slope of the power spectral density function on a log–log plot). While it is becoming increasingly clear that the characterization of either phase or amplitude scintillations by a single parameter may obscure significant characteristics of the scintillations, this simple approach has proven to be useful for the prediction of the behaviour of transionospheric propagation paths such as those used in various space application systems. This paper explores the use, in addition to the usual phase and amplitude observations, of measurements of angle-of-arrival, in order to characterize the scintillations. Since each of these observations represent a different kind of observational "filtering", the combination of one statistical parameter from each type of measurement should provide a more adequate characterization of the scintillations. It is found that the use of the widths of the autocorrelation functions for this purpose is preferred over the use of spectral indices.