On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation Study
Abstract High‐frequency (HF) ordinary polarized (O)‐mode waves transmitted along the Earth's geomagnetic field can excite plasma modes on both the bottomside and topside of the ionosphere, a process attributed to O‐to‐Z mode conversion. This mechanism explains how electromagnetic wave energy pe...
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| Format: | Article |
| Language: | English |
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Wiley
2025-08-01
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| Series: | Geophysical Research Letters |
| Online Access: | https://doi.org/10.1029/2025GL117286 |
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| _version_ | 1849236142668382208 |
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| author | Danish Naeem Dong‐Hun Lee Kihong Kim |
| author_facet | Danish Naeem Dong‐Hun Lee Kihong Kim |
| author_sort | Danish Naeem |
| collection | DOAJ |
| description | Abstract High‐frequency (HF) ordinary polarized (O)‐mode waves transmitted along the Earth's geomagnetic field can excite plasma modes on both the bottomside and topside of the ionosphere, a process attributed to O‐to‐Z mode conversion. This mechanism explains how electromagnetic wave energy penetrates beyond the resonance. However, a key question is whether Z‐mode waves interacting with the resonance remain confined or escape the ionosphere via Z‐to‐O conversion. While O‐to‐Z conversion is well studied, Z‐to‐O remains less explored, especially in the presence of field‐aligned irregularities. We use two‐dimensional finite‐difference time‐domain simulations to investigate Z‐mode interaction with the resonance, with and without field‐aligned density ducts, across a range of magnetic field angles. The results show that duct‐assisted Z‐to‐O conversion is highly angle‐dependent. We compare its efficiency with that of O‐to‐Z conversion, and discuss implications for the magnetic zenith effect. |
| format | Article |
| id | doaj-art-7a0b9895cfed4715bacd7a6abf80f702 |
| institution | Kabale University |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-7a0b9895cfed4715bacd7a6abf80f7022025-08-20T04:02:27ZengWileyGeophysical Research Letters0094-82761944-80072025-08-015215n/an/a10.1029/2025GL117286On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation StudyDanish Naeem0Dong‐Hun Lee1Kihong Kim2School of Space Research Kyung Hee University Yongin KoreaSchool of Space Research Kyung Hee University Yongin KoreaDepartment of Physics Ajou University Suwon KoreaAbstract High‐frequency (HF) ordinary polarized (O)‐mode waves transmitted along the Earth's geomagnetic field can excite plasma modes on both the bottomside and topside of the ionosphere, a process attributed to O‐to‐Z mode conversion. This mechanism explains how electromagnetic wave energy penetrates beyond the resonance. However, a key question is whether Z‐mode waves interacting with the resonance remain confined or escape the ionosphere via Z‐to‐O conversion. While O‐to‐Z conversion is well studied, Z‐to‐O remains less explored, especially in the presence of field‐aligned irregularities. We use two‐dimensional finite‐difference time‐domain simulations to investigate Z‐mode interaction with the resonance, with and without field‐aligned density ducts, across a range of magnetic field angles. The results show that duct‐assisted Z‐to‐O conversion is highly angle‐dependent. We compare its efficiency with that of O‐to‐Z conversion, and discuss implications for the magnetic zenith effect.https://doi.org/10.1029/2025GL117286 |
| spellingShingle | Danish Naeem Dong‐Hun Lee Kihong Kim On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation Study Geophysical Research Letters |
| title | On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation Study |
| title_full | On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation Study |
| title_fullStr | On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation Study |
| title_full_unstemmed | On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation Study |
| title_short | On the Role of Field‐Aligned Density Ducts in Z‐to‐O Mode Conversion in the Ionosphere: A 2D Simulation Study |
| title_sort | on the role of field aligned density ducts in z to o mode conversion in the ionosphere a 2d simulation study |
| url | https://doi.org/10.1029/2025GL117286 |
| work_keys_str_mv | AT danishnaeem ontheroleoffieldaligneddensityductsinztoomodeconversionintheionospherea2dsimulationstudy AT donghunlee ontheroleoffieldaligneddensityductsinztoomodeconversionintheionospherea2dsimulationstudy AT kihongkim ontheroleoffieldaligneddensityductsinztoomodeconversionintheionospherea2dsimulationstudy |