Simulating the Effects of Small-Scale Irregularities on HF Scintillation

The use of GNSS signals for global timing and positioning has become ubiquitous. These signals are frequently degraded or disrupted through interactions with multi-scale ionospheric irregularities, leading to both phase and amplitude scintillation. This necessitates an approach to understand both the growth and evolution of irregularities, as well as their interaction with radio waves. We demonstrate the use of FARR, a new finite-difference time-domain (FDTD) code that solves Maxwell’s equations, for modeling the interaction of HF radio waves with multi-scale plasma irregularities. Because the FDTD method is a full vector solution of Maxwell’s equations, we can explore the effects of small-scale irregularities, a regime geometric optics cannot model. Here we present simulations of HF communication through both the perturbed and background ionosphere. We also compare the FDTD approach with numerical ray tracing to evaluate the effects of small-scale gradients on phase and amplitude scintillation.