Inner core translation and the hemispheric balance of the geomagnetic field
Inner core translation and the hemispheric balance of the geomagnetic field
复制标题
内核平移与地磁场的半球平衡
DOI：
10.1016/j.epsl.2015.05.028
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发表时间：
2015
影响因子：
5.3
通讯作者：
Mound J
中科院分区：
文献类型：
--
作者：
Mound J
地球内核的整体平移被认为是观测到的准半球地震结构的一种解释。内核平移的一个重要后果是在内核边界（ICB）处产生一个球谐度为1的热流异常，这将为外核对流提供非均匀强迫。我们使用地球发电机模拟研究这种异质性的地磁信号。强烈的半球异质性在ICB被发现产生半球签名的磁场的形态和长期变化，特别是，我们注意到在我们的模型中形成的高强度通量补丁在高纬度地区和美洲热带地区具有较强的ICB异质性。在我们的模拟中，这个模型提供了最好的匹配地球的领域在过去的400年，根据以前提出的措施的领域结构。然而，这些标准并不包括能量场的半球平衡。我们提出了新的标准来衡量这种平衡，并发现我们的模型具有较强的ICB异质性产生最差的匹配历史地磁场的半球平衡。整个全新世的半球磁场平衡的分辨率将为任何快速内核平移的建议提供强有力的测试。
Bulk translation of the Earth's inner core has been proposed as an explanation of observed quasi-hemispheric seismic structure. An important consequence of inner core translation would be the generation of a spherical harmonic degree one heat flow anomaly at the inner core boundary (ICB) that would provide an inhomogeneous forcing for outer core convection. We use geodynamo simulations to investigate the geomagnetic signature of such heterogeneity. Strong hemispheric heterogeneity at the ICB is found to produce a hemispheric signature in both the morphology of the magnetic field and its secular variation; in particular, we note the formation of high-intensity flux patches at high-latitudes and American longitudes in our model with strong ICB heterogeneity. In our simulations, this model provides the best match to the Earth's field over the past 400 years according to previously proposed measures of field structure. However, these criteria do not include the hemispheric balance of the field. We propose new criteria to measure this balance and find that our model with strong ICB heterogeneity produces the poorest match to the hemispheric balance of the historical geomagnetic field. Resolution of the hemispheric balance of the magnetic field throughout the Holocene would provide a strong test of any proposal of rapid inner core translation.