Rapid Variations of Earth’s Core Magnetic Field

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