地核中MHD波的惯性模

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。

INERTIAL MODE OF MHD WAVE IN THE EARTH'S CORE

The outer core of the earth, being in the plasma state with high temperature, high pressure, high density, and immersed in a strong toroidal magnetic field, can support varieties of plasma waves. Under influene of earth rotation, MHD wave propagates alone field lines in two modes; eastward inertal mode and westward magnetic mode, both are characterized dy high dispersion. The magnetic mode is related with the secularvariation and westward shift of the main magnetic field. The inertial mode has periods of the order of days, its magnetic effects would be shielded from the earth''s surface dy conductive mantle. However, the mechanical couplins between the core and the lower mantle would be possidle, hence a periodic mechanic process would de produced by MHD wave in the earth''s core.