Nonlinear wave interactions as a model for naturally enhanced ion-acoustic lines in the ionosphere
Incoherent radar scatter from the ionosphere will, for equilibrium conditions, show two symmetric ion-acoustic lines, one for each direction of wave propagation. Many observation, from the EISCAT Svalbard Radar (ESR) for instance, demonstrate that the symmetry of this ion line can be broken, accompa...
| Main Authors: | , |
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| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
arXiv
2019
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.48550/arxiv.1905.03115 https://arxiv.org/abs/1905.03115 |
| Summary: | Incoherent radar scatter from the ionosphere will, for equilibrium conditions, show two symmetric ion-acoustic lines, one for each direction of wave propagation. Many observation, from the EISCAT Svalbard Radar (ESR) for instance, demonstrate that the symmetry of this ion line can be broken, accompanied by an enhanced, nonthermal, level of fluctuations, i.e., Naturally Enhanced Ion-Acoustic Lines (NEIALs). Several models have been proposed for explaining these naturally enhanced lines. Here, we consider one of these, suggesting that decay of electron beam excited Langmuir waves gives rise to enhanced asymmetric ion lines in the ionosphere. We use a weak-turbulence approximation, and identify crucial parameters for Langmuir decay processes to be effective in generating the observed signals. : 4 figures |
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