The paper Extreme Scintillation Structure Diagnostics, which has been submitted for publication, extends the development in the paper On phase screen models for scintillation diagnostics. The submitted paper is the basis for a talk to be presented at the Beacon Satellite Symposium in Rome, Italy during November 2025. The structure diagnostics paper summarizes phase-screen theoretical results used to interpret high-resolution (50 Hz) intensity and phase GNSS diagnostic receiver measurements.
The signal model and preprocessing operations to extract measures of the scintillation complex modulation are emphasized in the diagnostics paper. However, ideal structure diagnostics would reproduce an in-situ characterization of the electron density. Irregularity parameter estimation (IPE) is a formal procedure for estimating structure parameters that reconcile theoretical predictions and measurements. IPE is most effective when applied to a stochastic process characterized by a spectral density function. Diffraction-free diagnostic measurements would indeed reproduce in-situ characterizations. For example, TEC and path-integrated signal phase are structurally identical in the absence of diffraction. Thus, an implicit scintillation diagnostic objective is to accommodate or mitigate diffraction effects.
It is well known that free propagation is a perfectly reversable irrespective of scintillation intensity. The second paper exploits back propagation (BP) to mitigate diffraction. Upon validation using multiple phase screen (MPS) simulations, IPE applied to the phase extracted after BP is used to mitigate extreme scintillation. Data from a year campaign conducted at Hong Kong starting in 2013 and ending in 1015 show that two structure types are associated with equatorial plasma bubbles. The expected Equatorial Plasma Bubble (EPB) structure has two spatial wavenumber regimes characterized by inverse-power-law variations with power-law indices p1 and p2. The expected distribution has p1<p2. However, pronounced PPB structures with p1>p2 are observed in roughly equal numbers in the Hong Kong data.
It is possible that the structure change is associated with passes that are more nearly meridian aligned rather than cross field. Results are summarized in the BSS presentation Extreme Scintillation Observed During the May 24 Geomagnetic Storm
