MF/HF auroral radio emissions emanating from the topside ionosphere
MF/HF auroral radio emissions emanating from the topside ionosphere
复制标题
从顶部电离层发出的 MF/HF 极光无线电发射
DOI：
10.1029/2010gl043731
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
N. Sato and R. Fujii
中科院分区：
文献类型：
--
作者：
Sato;Y.;T. Ono;N. Sato and R. Fujii
本文简要报告了首次观测到的电离层顶面MF/HF极光射电辐射的偏振特征和源区。这些辐射被称为“地面百分辐射（THR）”，并被视为从地面可观察到的极光咆哮和MF爆发的对应物。THR通常发生在1.5-2.0 MHz和3.0-4.0 MHz附近的两个频带中的一个或两个中，其极化特征对应于L-O和R-X模式。R-X模是由两个上层混合波的非线性耦合引起的，它在极光咆哮和MF爆发中从未被报道过。Akebono卫星观测表明，在匹配条件fUH 2fce下，THR辐射在频率-时间图中与上层混合波合并。这一观测结果表明，在这种条件下，等离子体不稳定性增强了上部混合波，然后它们被转换为MF/HF极光射电发射。
This is a brief report on the first observation of polarization features and the source region of MF/HF auroral radio emissions emanating from the topside ionosphere. These emissions are called “Terrestrial Hectometric Radiation (THR)” and regarded as a counterpart of auroral roar and MF burst which are observable from the ground. THR typically occurs in either or both of two frequency bands near 1.5–2.0 MHz and 3.0–4.0 MHz, whose polarization features correspond to the L‐O and R‐X mode. The R‐X mode, which has never been reported as auroral roar and MF burst, can be attributed to nonlinear coupling of two upper hybrid waves. The Akebono satellite observation shows THR emissions merge with upper hybrid waves in a frequency‐time diagram under the matching conditionfUH∼ 2fce. This observation suggests that plasma instability enhances the upper hybrid waves under this condition, and then they are converted into MF/HF auroral radio emissions.