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地球外核处于高温、高压、高密度的等离子体状态,可以支持多种磁流体波的激发和传播。在地核中存在强的环型磁场,沿磁力传播的MHD波受到地球旋转的影响,分成东行的惯性模和西行的磁模,这两种波模具有高度色散的特点。其中西行磁模波与地磁场长期变化和西漂有关。东行惯性模波具有数天到数百天的周期,其磁效应被导电地幔所屏蔽,传不到地表,但它与下地幔物质可能发生力学耦合,在地幔中产生周期变化的力学过程,这种影响可能达及地表并在地表的地球物理现象中表现出来,它可能是某些周期性或韵律性地球物理现象的原因之一。
The Earth’s outer core is in a high-temperature, high-pressure, high-density plasma state and can support the excitation and propagation of a variety of magnetic fluid waves. There is a strong toroidal magnetic field in the Earth’s core. The MHD waves propagating along the magnetic force are affected by the rotation of the earth and are divided into the inertial modes in the east and the magnetic modes in the west. These two modes have highly dispersive characteristics. Among them, the westbound magnetic mode wave is related to the long-term change of the geomagnetic field and the west drift. The eastbound Inertial mode wave has a period of several days to hundreds of days. Its magnetic effect is shielded by the conductive mantle and can not reach the earth’s surface. However, it may undergo mechanical coupling with the material of the lower mantle and a mechanical process with periodic changes in the mantle. This effect may reach the surface and manifest itself in geophysical phenomena on the surface, which may be responsible for some of the periodic or rhythmical geophysical phenomena.