Standing Alfvén waves with m ≫ 1 in an axisymmetric magnetosphere excited by a stochastic source
Standing Alfvén waves with m ≫ 1 in an axisymmetric magnetosphere excited by a stochastic source
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随机源激发的轴对称磁层中 m ≫ 1 的阿尔文驻波
DOI：
10.1007/s00585-998-0900-5
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发表时间：
1998
影响因子：
1.9
通讯作者：
V. A. Mazur
中科院分区：
文献类型：
--
作者：
A. Leonovich;V. A. Mazur
在轴对称磁层模型的框架下，我们建立了随机源激发的宽带大方位波数m ~ 1的Alfvén驻波理论。电离层中的外部电流被视为振荡源。最后讨论了具有统计特性的“-白色噪声”源。它表明，这样的源驱动的振荡，也有"-白色噪声”的属性。阿尔芬驻波的每个谐波的这种振荡谱有两个最大值：靠近观察磁壳的极向和环向本征频率。在电离层中的小衰减的情况下，环向频率附近的最大值占主导地位，并且振荡几乎是环向极化的。随着大的衰减，最大值在极向频率附近占主导地位，并且振荡接近极向极化。
In the framework of an axisymmetric magnetospheric model, we have constructed a theory for broad-band standing Alfvén waves with large azimuthal wave numberm≫ 1 excited by a stochastic source. External currents in the ionosphere are taken as the oscillation source. The source with statistical properties of –white noise” is considered at length. It is shown that such a source drives oscillations which also have the –white noise” properties. The spectrum of such oscillations for each harmonic of standing Alfvén waves has two maxima: near the poloidal and toroidal eigenfre-quencies of the magnetic shell of the observation. In the case of a small attenuation in the ionosphere the maximum near the toroidal frequency is dominated, and the oscillations are nearly toroidally polarized. With a large attenuation, a maximum is dominant near the poloidal frequency, and the oscillations are nearly poloidally polarized.