Every five years, the international geomagnetic community come together to create a series of maps of the Earth’s main magnetic field. The maps are often referred to as models because they capture only some of the sources that produce the magnetic field at or above the surface. The International Geomagnetic Reference Field (IGRF) represents the main or core magnetic field which can be used for navigation by the general public or as a baseline for satellites to refer to. This will be the fourteenth update, hence the model is called IGRF-14.
The maps are updated every five years because the Earth’s main magnetic field changes slowly over time, 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 around 500 km above the surface.
The measurements are combined together in a mathematical manner to create two snapshots of the magnetic field five years in the past (2020) and slightly into the future (2025). The community also makes an estimate of how the magnetic field will change between 2025 and 2030. In 2030, we will go back and revise the 2025 map, make a new map for 2030 based on up to date measurements and then forecast to 2035.
A call has just been released to the community for IGRF-14. More information is available at the official IGRF page: https://www.ncei.noaa.gov/products/international-geomagnetic-reference-field.
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| IGRF-13 map of declination angle (in degrees east of west of True North) for 2020.0 |
- Dr. Ciaran Beggan, British Geological Survey (BGS)
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