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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ReplyDeleteThe International Geomagnetic Reference Field (IGRF)-14 is like the "gold standard" for Earth's magnetic field modeling. Imagine it as a mathematical snapshot of how the magnetic field behaves across the planet at a specific time. Scientists use it as a benchmark for all kinds of research and practical applications—anything from navigation systems to space exploration depends on knowing Earth's magnetic quirks.
ReplyDeleteWhat is IGRF?
The IGRF is a global model of Earth's magnetic field, constantly updated to stay accurate as the field shifts over time (spoiler: Earth's magnetic field is always on the move). It’s created by an international team of geophysicists who pool together measurements from satellites, observatories, and other sources to map out the field. The “14” in IGRF-14 simply means it's the 14th generation of this model, released in 2019.
Key Features of IGRF-14
It covers the magnetic field from 1900 to 2020, with predictions extending up to 2025.
The model works in spherical harmonics—essentially, a mathematical way of describing a 3D field.
It focuses on the Earth's core-generated field, though it also includes smaller contributions from the crust and external sources like solar winds.
Why is it Important?
Think about compasses, GPS, or even how animals like birds migrate—all these things rely on understanding Earth's magnetic field. For scientists, the IGRF helps study geomagnetic storms, tectonic activity, and even the Earth’s interior. It’s also a big deal for space missions since the magnetic field protects us from harmful solar radiation.
How Often is it Updated?
Because the magnetic field changes—thanks to complex processes in Earth’s molten core—the IGRF gets updated about every five years. These updates keep it as accurate as possible for scientific and practical use.
In short, IGRF-14 is a critical tool for understanding and navigating our magnetized world.
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