Solar Wind - Magnetosphere - Ionosphere Coupling: Signal Arrival Time and Perturbation Relations
Solar Wind - Magnetosphere - Ionosphere Coupling: Signal Arrival Time and Perturbation Relations
复制标题
太阳风-磁层-电离层耦合：信号到达时间和扰动关系
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
V. Vasyliūnas
中科院分区：
文献类型：
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作者：
P. Song;V. Vasyliūnas
[1]在一个简单的一维模型的基础上，我们描述了磁层顶重联开启后，从磁层顶到电离层的不同物理量的扰动序列，重联产生电场、电流、磁场和等离子体速度的扰动。这些扰动在很宽的频率范围内延伸，每个频带以其群速度传播到电离层。首先到达电离层的扰动主要是最高频率的电磁振荡，如果重联足够突然地开启，其前沿可以像光速一样快地传播，尽管如果重联只在哨声模式时间尺度上开启，它可能以哨声模式速度传播。在电流中占主导地位的振荡前沿以哨声模式的速度到达。扰动主要是在磁场和速度以及非振荡（阶跃函数）的变化，所有的数量到达最后，在阿尔芬速度。电离层在电磁锋到达后开始响应，尽管主要的变化发生在阿尔芬锋到达后。
[1] On the basis of a simple one-dimensional model, we describe the sequence of the perturbations of different quantities from the magnetopause to the ionosphere after reconnection at the magnetopause has been switched on. Reconnection produces perturbations in the electric field, current, magnetic field, and plasma velocity. These perturbations extend over a broad frequency range, and each frequency band propagates at its group velocity to the ionosphere. The first perturbations to arrive at the ionosphere are mainly electromagnetic oscillations carried by the highest frequencies, whose front can propagate as fast as the speed of light if reconnection has switched on sufficiently suddenly, although it may propagate at the whistler-mode speed if reconnection switches on only on the whistler-mode timescale. The front of oscillations predominantly in the current arrives next, at the whistler-mode speed. Perturbations predominantly in the magnetic field and the velocity as well as nonoscillatory (step-function) changes of all the quantities arrive last, at the Alfven speed. The ionosphere starts responding after the arrival of the electromagnetic front, although the dominant changes occur after the arrival of the Alfven front.