Evidence of fast variations in the Earth’s core field are seen both in magnetic observatory and satellite records. We present here how they have been identified at the Earth’s surface from ground-based observatory records and how their spatio-temporal structure is now characterised by satellite data. It is shown how their properties at the core mantle boundary are extracted through localised and global modelling processes, paying particular attention to their time scales. Finally are listed possible types of waves in the liquid outer core, together with their main properties, that may give rise to these observed fast variations.

中文翻译：

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地核磁场的快速变化

在磁天文台和卫星记录中都可以看到地球核心场快速变化的证据。我们在这里介绍如何从地面观测记录在地球表面识别它们，以及它们的时空结构现在如何通过卫星数据进行表征。它展示了它们在核心地幔边界的性质是如何通过局部和全球建模过程提取的，特别注意它们的时间尺度。最后列出了液体外核中可能的波类型，以及它们的主要特性，它们可能会导致这些观察到的快速变化。