In this study, the open-source finite-difference time-domain (FDTD) solvers gprMax, Elecode and MEEP are investigated for their suitability to compute lightning electromagnetic field propagation. Several simulations are performed to reproduce the results of typical field propagation scenarios that can be found in the literature. The results of the presented solvers are validated through comparison with reference field results corresponding to propagation over perfectly conducting and lossy ground. In most of the tested scenarios, all solvers reproduce the reference fields with satisfactory accuracy. However, close attention must be paid to the proper choice of the spatial discretization to avoid artificial numerical dispersion, and the application of the simulation cell boundaries, which can cause significant impairment of the results due to undesired reflections. Some cases of inaccurate FDTD results due to improper choices of parameters are demonstrated. Further, the features, the performance and limitations, and the advantages and drawbacks of the presented solvers are highlighted. For familiarization with the solvers' programmatical interfaces to initialize and run the simulations, the developed scripts are made available to the community in an openly accessible repository.

翻译：本研究针对开源时域有限差分（FDTD）求解器gprMax、Elecode与MEEP在计算雷电电磁场传播问题中的适用性展开探讨。通过执行多组仿真，复现了文献中典型的场传播场景结果。通过将所提求解器的计算结果与理想导电地面和有耗损地面传播的参考场结果进行对比，验证了其有效性。在大多数测试场景中，所有求解器均能以令人满意的精度复现参考场。然而，需特别注意空间离散化的合理选择以避免人为数值色散，同时需谨慎处理仿真单元边界的设置——不当的边界条件会因非期望反射导致结果严重失真。研究展示了若干因参数选择不当导致FDTD结果不准确的具体案例。此外，本文重点分析了各求解器的功能特性、性能局限及其优缺点。为帮助研究者熟悉通过编程接口初始化并运行仿真的流程，相关开发脚本已发布于开放访问的代码仓库中。