Overview:
- The Earth’s Magnetic Environment
- ESA Swarm Mission
- Secular variation: Jerks, IGRF and Model Updates
- Modelling Uncertainties
- Summary
Earth’s Magnetic Field:
- Dominant core field varies over months to years (±60,000 nT)
- Fields due to complex current systems in the ionosphere and magnetosphere vary from seconds to years (±60 nT)
- Localised crustal field stable through time (±10 nT)
- Now resolving ocean tides induced fields (±2 nT) Credit: GFZ,DTU 44th General Meeting September 22nd, 2016 Glasgow, Scotland, UK Wellbore Positioning Technical Section
Global Magnetic Field Modelling:
- Spherical harmonic ‘degree’ of model represents spatial resolution
- Produced annually since 1990s
- A high temporal and spatial resolution
- Most models describe time-varying main field and include crustal and some external fields
- Accurately quantified errors (compared against ground measurements)
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Using Swarm Satellite Data to Improve Global Geomagnetic Reference Modeling
Ciarán Beggan