Source-Receiver Ionospheric-Scintillation Global Model of the Upper Atmosphere (SIGMA): Sensitivity Analysis

We have performed a sensitivity analysis using the Source-receiver Ionospheric-scintillation Global Model of the upper Atmosphere (SIGMA) multiple phase screen based forward propagation model to explore the relationship between the number of phase screens and the convergence of amplitude and phase scintillation estimates. It was found that for highly elongated vertical irregularities that phase scintillation solutions converge when using as few as 2 or 3 phase screens while as many as 10 to 15 screens are needed for amplitude scintillation estimates to converge. It was also shown that following convergence that the addition of more screens leads to an apparent divergence of solutions which suggests a limitation to the propagation solution utilized in the current version of SIGMA. These results provide invaluable insight into the need to carefully analyze a phase screen model setup in order achieve the accuracy required for a particular application given a set of input parameters.