阿尔芬波在低纬电离层中传播的数值模拟

Numerical Simulation of Alfvén Waves Propagating Through the Low-Latitude Ionosphere

从描述空间冷等离子体波动的双流体动力学方程出发,模拟了低纬电离层顶部的周期场向电流脉冲激发的阿尔芬波在电离层中的传播过程,分析了阿尔芬波在低纬电离层中的反射和耦合.结果表明,在谐振器下边界沿磁力线方向传播的剪切阿尔芬波会发生明显反射(反射系数(R)≥0.6),当剪切阿尔芬波频率位于谐振器共振频率附近时,剪切阿尔芬波在反射过程中将激发垂直于背景磁场传播的压缩阿尔芬波,其扰动磁场将可能形成当地观测的短周期地磁脉动.该结果为从理论上解释地磁脉动现象提供了一种理论依据.

Based on the two-fluid dynamics equations describing plasma flow in a cold magnetized medium, the propagation of Alfvén waves initialized by a one-period-time field-aligned current at the top of the low-latitude ionosphere has been stimulated, the reflection and coupling of Alfvén wave in the low-latitude ionosphere has been analyzed. The results show the reflection coefficient is larger at the bottom end of resonator, and the shear wave is reflected distinctly （reflection coefficient （R）≥0.6）. If wave frequency is approximately equal to the cavity mode frequency, compressional Alfvén wave that propagates across background magnetic field lines is generated while reflection occurs, then the disturbed magnetic field has effect to the local geomagnetic pulsations. And the results prouide a scientific warranty to explain the phenomena of the geomagentic pulsations.