Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation
Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation
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DOI：
10.1038/s41561-020-0570-9
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发表时间：
2020-05-05
影响因子：
18.3
通讯作者：
Bayliff, Matthew
中科院分区：
文献类型：
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作者：
Livermore, Philip W.;Finlay, Christopher C.;Bayliff, Matthew
基于观测的模型表明，最近地球北磁极向西伯利亚的加速可能与加拿大下面的核幔边界处的负磁通量瓣的伸长有关。地球北磁极的漂移，即磁场垂直向下的位置，长期以来一直是科学魅力的主题。自1831年首次在加拿大北极地区进行现场测量以来，北极一直无情地向西伯利亚漂移，从1990年到2005年，从历史上的0-15公里/年加速到目前的50-60公里/年。2017年10月下旬，北磁极越过国际日期变更线，在距离地理极点390公里的范围内通过，现在正在向南移动。在这里，我们表明，在过去的二十年中，北磁极的位置在很大程度上是由两个大规模的瓣的负磁通量的核幔边界在加拿大和西伯利亚。局部模型显示，加拿大叶的伸长，可能是由于1970年至1999年期间核心流模式的改变，大大削弱了其在地球表面的特征，导致极点加速向西伯利亚移动。一系列捕捉到这一过程的简单模型表明，在未来十年内，北磁极将继续沿着目前的轨道前进，向西伯利亚方向前进390-660公里。
Observation-based modelling suggests that recent acceleration of Earth's north magnetic pole towards Siberia can be linked to elongation of a lobe of negative magnetic flux at the core-mantle boundary beneath Canada.The wandering of Earth's north magnetic pole, the location where the magnetic field points vertically downwards, has long been a topic of scientific fascination. Since the first in situ measurements in 1831 of its location in the Canadian arctic, the pole has drifted inexorably towards Siberia, accelerating between 1990 and 2005 from its historic speed of 0-15 km yr(-1) to its present speed of 50-60 km yr(-1). In late October 2017 the north magnetic pole crossed the international date line, passing within 390 km of the geographic pole, and is now moving southwards. Here we show that over the last two decades the position of the north magnetic pole has been largely determined by two large-scale lobes of negative magnetic flux on the core-mantle boundary under Canada and Siberia. Localized modelling shows that elongation of the Canadian lobe, probably caused by an alteration in the pattern of core flow between 1970 and 1999, substantially weakened its signature on Earth's surface, causing the pole to accelerate towards Siberia. A range of simple models that capture this process indicate that over the next decade the north magnetic pole will continue on its current trajectory, travelling a further 390-660 km towards Siberia.