On the Mutual Coherence Function for Transionospheric Waves and its Utility for Characterizing Ionospheric Irregularities with a GNSS Scintillation Monitor

When interpreting GNSS observations of ionospheric scintillation, it is instructive to distinguish between the separate goals of characterizing the GNSS signal fluctuations and characterizing the disturbed ionospheric medium that produces the scintillations. The statistics of GNSS signal fluctuations are of primary interest for GNSS tracking loop analysis and design studies intended to quantify and model the impacts of ionospheric scintillation on navigation accuracy. Conversely, from an ionospheric physics standpoint, of primary interest are the statistical characteristics of the random ionospheric medium itself, and how these relate to the physical processes that structure the plasma. When the scintillation is weak, receiver diagnostics can serve both applications because the spectra of signal fluctuations at the ground are simply related to the spectra of variations in the ionospheric density.