地幔底部的Electrical conductivity解释了地核扭转波在赤道的吸收
Electrical conductivity of the lowermost mantle explains absorption of core torsional waves at the equator
摘要：
通过应用于地磁模型的反演技术，已经推断出在地核中传播的扭转阿尔夫文波。它们似乎在地核传播，但在赤道消失，在地核和地幔之间交换角动量。假设轴对称，我们发现，在地幔底部的导电层可以导致总吸收的扭转波到达赤道。我们表明，反射系数取决于GBr，其中Br是径向磁场在赤道的强度，和G的下地幔那里的电导。当Br = 7 e-4 T时，当G = 1.3e8S时，扭转波在赤道上被完全吸收。对于较大或较小的G，发生反射。当G增加到该临界值以上时，存在更少的衰减和更多的角动量交换。我们的发现分离有效的核幔耦合从地幔中的强欧姆耗散。
英文摘要：
Torsional Alfv{é}n waves propagating in the Earth's core have been inferred by inversion techniques applied to geomagnetic models. They appear to propagate across the core but vanish at the equator, exchanging angular momentum between core and mantle. Assuming axial symmetry, we find that an electrically conducting layer at the bottom of the mantle can lead to total absorption of torsional waves that reach the equator. We show that the reflection coefficient depends on G Br , where Br is the strength of the radial magnetic field at the equator, and G the conductance of the lower mantle there. With Br = 7e-4 T., torsional waves are completely absorbed when they hit the equator if G = 1.3e8 S. For larger or smaller G, reflection occurs. As G is increased above this critical value, there is less attenuation and more angular momentum exchange. Our finding dissociates efficient core-mantle coupling from strong ohmic dissipation in the mantle.
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