Modeling in-ice radio propagation with parabolic equation methods

TL;DR

This paper explores parabolic equation methods for modeling radio-wave propagation in polar ice, offering a computationally efficient alternative to full-field solutions and more detailed than geometric ray-tracing, with implications for neutrino detection experiments.

Contribution

The paper introduces a new PE approximation tailored for in-ice radio propagation, highlighting its advantages over existing methods and discussing its impact on neutrino detection sensitivity.

Findings

PE methods are more flexible than RT and more efficient than FDTD.

Current RT methods may overestimate detector sensitivity.

PE methods could improve modeling accuracy for in-ice radio detection.

Abstract

We investigate the use of parabolic equation (PE) methods for solving radio-wave propagation in polar ice. PE methods provide an approximate solution to Maxwell's equations, in contrast to full-field solutions such as finite-difference-time-domain (FDTD) methods, yet provide a more complete model of propagation than simple geometric ray-tracing (RT) methods that are the current state of the art for simulating in-ice radio detection of neutrino-induced cascades. PE are more computationally efficient than FDTD methods, and more flexible than RT methods, allowing for the inclusion of diffractive effects, and modeling of propagation in regions that cannot be modeled with geometric methods. We present a new PE approximation suited to the in-ice case. We conclude that current ray-tracing methods may be too simplistic in their treatment of ice properties, and their continued use could overestimate experimental sensitivity for in-ice neutrino detection experiments. We discuss the implications for current in-ice Askaryan-type detectors and for the upcoming Radar Echo Telescope; two families of experiments for which these results are most relevant. We suggest that PE methods be investigated further for in-ice radio applications.