Possible generation mechanisms of the Pi2 pulsations estimated from a global MHD simulation
Possible generation mechanisms of the Pi2 pulsations estimated from a global MHD simulation
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根据全局 MHD 模拟估计的 Pi2 脉动的可能生成机制
DOI：
10.5047/eps.2012.11.005
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
T. Tanaka
中科院分区：
文献类型：
--
作者：
S. Fujita;T. Tanaka
等离子体层虚拟共振（PVR）和在两半球电离层之间反弹的瞬态Alfvén波（瞬态响应，TR）被认为是Pi2脉动的可能产生机制。然而，亚暴的全球MHD模拟（Tanaka等人，2010年）并没有重现这样的波模式，因为阿尔文波的电离层反射不足，阿尔文波穿过场线的数值传输，以及没有等离子体振荡。此外，它是注意到，亚暴电流楔（SCW），这是一个驱动器的TR是没有重现在全球MHD模拟。在这项研究中，我们搜索的全球MHD模拟中的Pi2脉动的来源，即，在磁层内的PVR和Alfvén波注入电离层的TR的压缩波。总之，当亚暴爆发时高速的向地气流在等离子体片的内边缘涌动时，内磁层中出现了压缩信号。这个模拟结果表明，如果模型具有等离子体屏蔽，则该压缩波将被捕获在等离子体屏蔽中作为PVR。至于TR，全球MHD模拟提供了突然增加的场向电流（Alfvén波），与剪切流的突然出现有关，剪切流来自亚暴开始时等离子体片中的高速流动。如果全球MHD模拟正确地让阿尔文波在电离层中反射并沿场线沿着传播，TR将被建立。由于气球不稳定性被认为是Pi2脉动源的候选者之一，我们还简要地研究了在生长阶段的模拟等离子体片是否是不稳定的气球不稳定性。
The plasmaspheric virtual resonance (PVR) and the transient Alfvén wave bouncing between the ionospheres in both hemispheres (the transient response, TR) are regarded as the possible generation mechanisms of the Pi2 pulsations. However, the global MHD simulation of a substorm (Tanaka et al., 2010) did not reproduce such wave modes because of insufficient ionospheric reflection of the Alfvén wave, numerical transfer of the Alfvén wave across the field lines, and no plasmasphere. Furthermore, it is noted that the substorm current wedge (SCW) which is a driver of the TR is not reproduced in the global MHD simulation. In this study, we search the sources of the Pi2 pulsations in the global MHD simulation, namely, the compressional wave in the inner magnetosphere for the PVR and the Alfvén wave injected to the ionosphere for the TR. In conclusion, there appears a compressional signal in the inner magnetosphere when the high-speed Earthward flow at the substorm onset surges in the inner edge of the plasma sheet. This simulation result suggests that this compressional wave would be trapped in the plasmasphere as the PVR if the model has the plasmasphere. As for TR, the global MHD simulation provides suddenly increasing field-aligned current (the Alfvén wave) associated with sudden appearance of the shear flow which comes from the high-speed flow in the plasma sheet at the onset of the substorm. If the global MHD simulation correctly lets the Alfvén wave be reflected in the ionosphere and transmitted along the field line, the TR would be established. As the ballooning instability is regarded as one of candidates of the Pi2 pulsation sources, we also briefly investigate whether the simulated plasma sheet in the growth phase is unstable or not for the ballooning instability.
地面高纬度地区观测到的Pi 2 磁脉动的传播特征
DOI：
--
发表时间：
2004
期刊：
Journal of Geophysical Research 109
影响因子：
--
作者：
Uozumi;T;K.Yumoto;H.Kawano;A.Yosikawa;S.Ohtani;J.V.Olson;S.-I.Akasofu;S.I.Solovyev6;E.F.Vershinin;k.Liou;C.-I.Meng
通讯作者：
C.-I.Meng
与亚暴流楔相关的 Pi2 脉动的数值模拟
DOI：
--
发表时间：
2002
期刊：
Journal of Geophysical Research 107
影响因子：
--
作者：
石田邦光;大島慶一郎;S.Fujita;S.Fujita
通讯作者：
S.Fujita