论文标题
由于最低地幔的高电导率，弱磁场在太平洋上变化
Weak magnetic field changes over the Pacific due to high conductance in lowermost mantle
论文作者
论文摘要
在过去的几个世纪中，太平洋地区地球磁场的时间变化异常低。其原因与核心外轴附近的液体外核的大规模流相关，在太平洋下方较弱，并具有偏心且广泛避开该区域的行星尺度回旋。但是，调节这种流动形态的是未知的。在这里，我们介绍了地球芯中动力学的数值模型的结果，该模型包括电磁耦合与地幔底部的不均匀导电层。我们表明，当太平洋在太平洋下的电导率高于其他地方时，较大的电磁阻力会削弱局部核心流量，并偏转行星gyre的流动远离太平洋。最低地幔电导的性质尚不清楚，但是捕获在核心壳边界的地形上的核心流体是一个可能的解释。
For the past few centuries, the temporal variation in the Earth's magnetic field in the Pacific region has been anomalously low. The reason for this is tied to large scale flows in the liquid outer core near the core-mantle boundary, which are weaker under the Pacific and feature a planetary scale gyre that is eccentric and broadly avoids this region. However, what regulates this type of flow morphology is unknown. Here, we present results from a numerical model of the dynamics in Earth's core that includes electromagnetic coupling with a non-uniform conducting layer at the base of the mantle. We show that when the conductance of this layer is higher under the Pacific than elsewhere, the larger electromagnetic drag force weakens the local core flows and deflects the flow of the planetary gyre away from the Pacific. The nature of the lowermost mantle conductance remains unclear, but stratified core fluid trapped within topographic undulations of the core-mantle boundary is a possible explanation.
