An open source code for modeling radio wave propagation in earth’s ionosphere
We present FARR (Finite-difference time-domain ARRay), an open source, high-performance, finite-difference time-domain (FDTD) code. FARR is specifically designed for modeling radio wave propagation in collisional, magnetized plasmas like those found in the Earth’s ionosphere. The FDTD method directl...
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Frontiers Media S.A.
2025-02-01
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| Series: | Frontiers in Astronomy and Space Sciences |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fspas.2025.1521497/full |
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| author | Alexander Green William J. Longley Meers M. Oppenheim Matthew A. Young |
| author_facet | Alexander Green William J. Longley Meers M. Oppenheim Matthew A. Young |
| author_sort | Alexander Green |
| collection | DOAJ |
| description | We present FARR (Finite-difference time-domain ARRay), an open source, high-performance, finite-difference time-domain (FDTD) code. FARR is specifically designed for modeling radio wave propagation in collisional, magnetized plasmas like those found in the Earth’s ionosphere. The FDTD method directly solves Maxwell’s equations and captures all features of electromagnetic propagation, including the effects of polarization and finite-bandwidth wave packets. By solving for all vector field quantities, the code can work in regimes where geometric optics is not applicable. FARR is able to model the complex interaction of electromagnetic waves with multi-scale ionospheric irregularities, capturing the effects of scintillation caused by both refractive and diffractive processes. In this paper, we provide a thorough description of the design and features of FARR. We also highlight specific use cases for future work, including coupling to external models for ionospheric densities, quantifying HF/VHF scintillation, and simulating radar backscatter. The code is validated by comparing the simulated wave amplitudes in a slowly changing, magnetized plasma to the predicted amplitudes using the WKB approximation. This test shows good agreement between FARR and the cold plasma dispersion relations for O, X, R, and L modes, while also highlighting key differences from working in the time-domain. Finally, we conclude by comparing the propagation path of an HF pulse reflecting from the bottomside ionosphere. This path compares well to ray tracing simulations, and demonstrates the code’s ability to address realistic ionospheric propagation problems. |
| format | Article |
| id | doaj-art-91128d6f529a459eb640dbabf6456d0a |
| institution | Kabale University |
| issn | 2296-987X |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Astronomy and Space Sciences |
| spelling | doaj-art-91128d6f529a459eb640dbabf6456d0a2025-02-04T06:31:40ZengFrontiers Media S.A.Frontiers in Astronomy and Space Sciences2296-987X2025-02-011210.3389/fspas.2025.15214971521497An open source code for modeling radio wave propagation in earth’s ionosphereAlexander Green0William J. Longley1Meers M. Oppenheim2Matthew A. Young3Center for Space Physics, Boston University, Boston, MA, United StatesCenter for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, NJ, United StatesCenter for Space Physics, Boston University, Boston, MA, United StatesSpace Science Center, University of New Hampshire, Durham, NH, United StatesWe present FARR (Finite-difference time-domain ARRay), an open source, high-performance, finite-difference time-domain (FDTD) code. FARR is specifically designed for modeling radio wave propagation in collisional, magnetized plasmas like those found in the Earth’s ionosphere. The FDTD method directly solves Maxwell’s equations and captures all features of electromagnetic propagation, including the effects of polarization and finite-bandwidth wave packets. By solving for all vector field quantities, the code can work in regimes where geometric optics is not applicable. FARR is able to model the complex interaction of electromagnetic waves with multi-scale ionospheric irregularities, capturing the effects of scintillation caused by both refractive and diffractive processes. In this paper, we provide a thorough description of the design and features of FARR. We also highlight specific use cases for future work, including coupling to external models for ionospheric densities, quantifying HF/VHF scintillation, and simulating radar backscatter. The code is validated by comparing the simulated wave amplitudes in a slowly changing, magnetized plasma to the predicted amplitudes using the WKB approximation. This test shows good agreement between FARR and the cold plasma dispersion relations for O, X, R, and L modes, while also highlighting key differences from working in the time-domain. Finally, we conclude by comparing the propagation path of an HF pulse reflecting from the bottomside ionosphere. This path compares well to ray tracing simulations, and demonstrates the code’s ability to address realistic ionospheric propagation problems.https://www.frontiersin.org/articles/10.3389/fspas.2025.1521497/fullFDTDscintillationradio wave propagationionospheric propagationopen sourceionospheric irregularities |
| spellingShingle | Alexander Green William J. Longley Meers M. Oppenheim Matthew A. Young An open source code for modeling radio wave propagation in earth’s ionosphere Frontiers in Astronomy and Space Sciences FDTD scintillation radio wave propagation ionospheric propagation open source ionospheric irregularities |
| title | An open source code for modeling radio wave propagation in earth’s ionosphere |
| title_full | An open source code for modeling radio wave propagation in earth’s ionosphere |
| title_fullStr | An open source code for modeling radio wave propagation in earth’s ionosphere |
| title_full_unstemmed | An open source code for modeling radio wave propagation in earth’s ionosphere |
| title_short | An open source code for modeling radio wave propagation in earth’s ionosphere |
| title_sort | open source code for modeling radio wave propagation in earth s ionosphere |
| topic | FDTD scintillation radio wave propagation ionospheric propagation open source ionospheric irregularities |
| url | https://www.frontiersin.org/articles/10.3389/fspas.2025.1521497/full |
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