BGS leads update to maps of the Earth’s magnetic field

The International Geomagnetic Reference Field (IGRF), which represents the main or core magnetic field of the Earth, is collaboratively updated by the international geomagnetic community, including BGS’s geomagnetism team. This will be the fourteenth update (IGRF-14) and is due for completion at the end of 2024. IGRF can be used for many purposes, such as navigation by spacecraft that are used for orientation.

In collaboration with the US National Oceanic and Atmospheric Administration, BGS will also update the World Magnetic Model (WMM) at the end of this year. The WMM is a series of magnetic field maps that help underpin commercial navigation systems, such as electronic devices including mobile phones, and is also updated every five years.

The maps require periodic updates because the Earth’s main magnetic field changes slowly over time, which is caused by flow of the liquid iron in the outer core. Measurements of the magnetic field are made at geomagnetic observatories on the ground and by specialist satellites that orbit around 500 km above the surface. 

The measurements are combined using computers to create two snapshots of the magnetic field: one five years in the past (2020) and the other slightly into the future (2025). The geomagnetic community also makes an estimate of how the magnetic field will change between 2025 and 2030. In 2030, this process will be repeated, in order to forecast to 2035. 

The call for candidate models for IGRF-14 was recently released to the community. The coordination of the release for this generation is led by Dr Ciarán Beggan at BGS and Clemens Kloss at the Technical University of Denmark and will involve dozens of scientists from around the world helping to create the new maps.

These maps are embedded in nearly every mobile phone in the world — that’s almost 7 billion devices, which I find amazing to think about.

Ciarán Beggan, BGS Geophysicist.

The 2019 model update showed magnetic north racing across the northern hemisphere at around 50 km per year, as it moved from the Canadian Arctic towards Siberia.

More information

More information on the call for candidate models is available at the official IGRF page.