The magnetoionic modes and propagation properties of auroral radio emissions
The magnetoionic modes and propagation properties of auroral radio emissions
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DOI：
10.1029/ja095ia04p03943
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发表时间：
1990-04
影响因子：
--
通讯作者：
W. Calvert;K. Hashimoto
中科院分区：
文献类型：
--
作者：
W. Calvert;K. Hashimoto
不同的磁离子波模式，伴随着极光确定使用DE 1不仅通过它们的出现在卫星无线电频谱图，但也通过同时测量它们的波偏振和到达方向，并通过射线跟踪模型的预期传播行为。在四种可能的传播模式中，分别指定为O，X，W和Z，分别代表普通，非常，哨声和Z模式，所有四种模式都发生在极光区，如下所示：当然，最强烈的是众所周知的极光千米辐射（AKR），它主要起源于电子回旋频率附近的X模式，但是其经常还伴随有来自相同位置的较弱O模式分量。下一个最突出的极光发射是W模式的极光嘶嘶声，其频率低于当地回旋频率，起源于DE 1卫星远低于的高度。先前报道的Z模式极光辐射也被检测到，但也来自卫星下方和腔体向极边缘的来源，而不是来自回旋加速器频率的预期AKR源。一个较弱的O模式分量似乎也伴随着这些发射，无论是在极帽极向的源和内部更多的腔，后者似乎是由腔的较低的等离子体密度向上引导。最后，正是在源场线在极向边缘的腔，也偶尔似乎是本地化的Z模式发射延伸从Z模式截止在相当低的频率高达和以上的等离子体频率。«少
The different magnetoionic wave modes which accompany the aurora are identified using DE 1 not only by their appearance on satellite radio spectrograms, but also by concurrent measurements of their wave polarization and arrival directions, and by ray-tracing models of their expected propagation behavior. Of the four possible propagation modes, designated O, X, W, and Z for the ordinary, extraordinary, whistler, and Z modes, respectively, all four are found to occur in the auroral zone, as follows: The most intense, of course, is the well-known auroral kilometric radiation (AKR), which originates primarily in the X mode near the electron cyclotron frequency, but which is frequently also accompanied by a weaker O-mode component from the same location. The next most prominent auroral emission is the W-mode auroral hiss originating from altitudes always well below the DE 1 satellite at frequencies below the local cyclotron frequency. The previously reported Z-mode auroral radiation was also detected, but from sources also below the satellite and at the poleward edge of the cavity, and not from the expected AKR source at the cyclotron frequency. A weaker O-mode component seems to accompany these emissions also, both within the polar cap poleward of the source and insidemore » the cavity, the latter seemingly being guided upward by the cavity's lower plasma densities. Finally, exactly on the source field lines at the poleward edge of the cavity, there also occasionally seems to be localized Z-mode emissions extending from the Z-mode cutoff at quite low frequencies up to and above the plasma frequency.« less