Ionospheric conductance distribution and MHD wave structure: observation and model
Ionospheric conductance distribution and MHD wave structure: observation and model
复制标题
电离层电导分布和 MHD 波结构：观测和模型
DOI：
10.1007/s00585-998-0140-8
复制
发表时间：
1998
影响因子：
1.9
通讯作者：
S. Buchert
中科院分区：
文献类型：
--
作者：
F. Budnik;M. Stellmacher;K. Glassmeier;S. Buchert
电离层影响磁层中的磁流体动力学波的阻尼，因为焦耳加热和改变波的结构本身。当Pedersen高度积分电导率超过一个临界值，即磁层波导时，三维环向波方程将出现不同的本征值和本征解。因此，在超低频脉动记录中可以观察到频率的跳跃。这种效应主要发生在佩德森电导梯度的区域，如极光椭圆区或黎明和黄昏区。本文介绍了地球静止轨道GOES-6卫星记录的一次脉动事件。我们解释所观察到的频率变化作为一个变化的波结构，而穿越终结者。此外，在偶极磁层与现实的电离层条件的数值模拟的结果进行了讨论。这些与观测数据非常一致。
The ionosphere influences magnetohydrodynamic waves in the magnetosphere by damping because of Joule heating and by varying the wave structure itself. There are different eigenvalues and eigensolutions of the three dimensional toroidal wave equation if the height integrated Pedersen conductivity exceeds a critical value, namely the wave conductance of the magnetosphere. As a result a jump in frequency can be observed in ULF pulsation records. This effect mainly occurs in regions with gradients in the Pedersen conductances, as in the auroral oval or the dawn and dusk areas. A pulsation event recorded by the geostationary GOES-6 satellite is presented. We explain the observed change in frequency as a change in the wave structure while crossing the terminator. Furthermore, selected results of numerical simulations in a dipole magnetosphere with realistic ionospheric conditions are discussed. These are in good agreement with the observational data.