Rapid Variations of Earth's Core Magnetic Field

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.

Automated summary

This paragraph discusses the evidence of fast variations in the Earth's core field observed in magnetic observatory and satellite records. It explains how these variations are identified at the Earth's surface and characterized by satellite data. The paragraph also mentions the extraction of their properties at the core mantle boundary through localized and global modeling processes, with emphasis on their time scales. Finally, it lists the possible types of waves in the liquid outer core that may cause these observed fast variations.