The nature of reflection and mode conversion of MHD waves in the inductive ionosphere: Multistep mode conversion between divergent and rotational electric fields
The nature of reflection and mode conversion of MHD waves in the inductive ionosphere: Multistep mode conversion between divergent and rotational electric fields
复制标题
感应电离层中 MHD 波的反射和模式转换的本质：发散电场和旋转电场之间的多步模式转换
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
M. Itonaga
中科院分区：
文献类型：
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作者：
A. Yoshikawa;M. Itonaga
从波模电流守恒定律出发，分析了磁流体波在高纬感应电离层上的反射和模式转换的本质。感应电离层是指剪切阿尔芬波在电离层上反射过程中产生的非零旋转电场或非零压缩磁场。有限旋转电场引起电离层中发散电流系统和旋转电流系统之间的互感。剪切阿尔芬波的发散电场的一步霍尔效应产生旋转霍尔电流，激发电离层表面压缩波。电离层表面压缩波的旋转电场的霍尔效应产生发散的霍尔电流（两步霍尔效应），其将压缩磁能反馈到反射的场向电流。我们发现，电离层旋转电场对剪切阿尔芬波反射过程的重正化导致了电离层电流和模式转换波磁场分布的一些特殊性。这种特性在高传导电离层中变得特别明显。例如，在电离层电流分布中，电离层发散电流的相当大的分量由发散霍尔电流占。旋转霍尔电流和彼得森电流相互抵消，导致总的电离层旋转电流为零。从入射剪切阿尔芬波的环向磁场传输的极向磁场的振幅显示出对Δ H/Δ Tp的非线性依赖性。它还显示了一种新的类型的有效的电离层屏蔽效应在一个固定的电离层屏蔽条件下，在参数空间中的EHp/EHp A。我们断言，电离层的感应响应应该成为一个不可或缺的概念，反射，模式转换，传输，并产生各种现象有关的场向电流系统。
The nature of reflection and mode conversion of MHD waves at the high-latitudinal inductive ionosphere is analyzed, based on the current conservation law of wave modes. The term “inductive ionosphere” refers to the nonzero rotational electric field or nonzero compressional magnetic field in the reflection process of shear Alfven waves on the ionosphere. The finite rotational electric field causes mutual induction between the divergent and rotational current systems at the ionosphere. The one-step Hall effect for the divergent electric field of the shear Alfven wave produces a rotational Hall current and excites the ionospheric surface compressional wave. The Hall effect for the rotational electric field of an ionospheric surface compressional wave produces a divergent Hall current (two-step Hall effect), which feeds back the compressional magnetic energy to the reflected field-aligned current. We find that the renormalization of the ionospheric rotational electric field to the reflection process of the shear Alfven wave causes some peculiarities in the distribution of ionospheric currents and mode-converted wave magnetic fields. Such peculiarities become particularly obvious in the high-conducting ionosphere. For example, in the ionospheric current distributions, a considerable component of the ionospheric divergent current is accounted for by the divergent Hall current. The rotational Hall and Pedersen currents cancel each other out and lead to zero total ionospheric rotational current. The amplitude of the poloidal magnetic field transmitted from the toroidal magnetic field of the incident shear Alfven wave shows a nonlinear dependence on ΣH/Σp. It also shows a new type of effective ionospheric shielding effect in the Σp/ΣA parameter space for a fixed ΣH/Σp condition. We assert that the inductive response of the ionosphere should become an indispensable concept for reflection, mode conversion, transmission, and generation of various phenomena relating to the field-aligned current system.