The latest version of the World Magnetic Model (WMM), one of the key tools developed to model the change in Earth's magnetic field, has been released. The WMM is a spherical harmonic model of the Earth’s main magnetic field and its slow temporal change. The WMM is key to global navigation, ensuring that technological systems relying on the Earth’s magnetic field operate correctly.
The World Magnetic Model 2025 (WMM2025) provides more precise navigational data for all military and civilian planes, ships, submarines, and GPS units. This year, two versions of the model are being released. In addition to WMM2025, the release includes the first-ever World Magnetic Model High Resolution (WMMHR2025), which includes improved spatial resolution of approximately 300 kilometers at the equator compared to the standard spatial resolution of 3300 kilometers at the equator. Higher resolution provides greater directional accuracy. Users are encouraged to transition to this higher resolution model.
The blackout zones introduced in the previous version have been updated in WMM2025 to represent slight shifts in their location. These zones, near the North and South poles, indicate where the Earth’s magnetic field can be unusable for navigation.
Model Cooperation
Because the WMM is crucial for accurate navigation and the Earth’s magnetic field changes in unpredictable ways over time, particularly over periods longer than a few years, the WMM is updated at least every five years. Compasses are influenced by Earth's magnetic field, so having an up-to-date model ensures that navigational instruments provide correct readings.
The WMM is the standard model used by the United Kingdom and the United States governments, including the U.S. Federal Aviation Administration and the U.S. Department of Defense, as well as organizations with an international remit such as the North Atlantic Treaty Organization (NATO), and the International Hydrographic Organization, and the UK Hydrographic Office. Smartphone and consumer electronics companies also rely on the WMM to provide consumers with accurate compass apps, maps, and GPS services.
The WMM is jointly developed by NOAA National Centers for Environmental Information (NCEI) and the British Geological Survey (BGS) and is a joint product of the United States’ National Geospatial-Intelligence Agency (NGA) and the United Kingdom’s Defence Geographic Centre (DGC). The model, associated software, and documentation are distributed by NCEI on behalf of the NGA and by BGS on behalf of DGC.
NCEI and the WMM
NCEI, with support from the Cooperative Institute for Research in Environmental Sciences (CIRES), plays a critical role in the development, maintenance, and distribution of the WMM.
NCEI develops and distributes models of the geomagnetic field and maintains archives of geomagnetic data to further the understanding of Earth magnetism and its dynamic changes. NCEI also provides tools and services to visualize, access, and utilize the WMM and other geomagnetic data products and models.
NCEI collaborates with partners to conduct research to better understand Earth's magnetic field, its variations, and its potential impact on Earth and its technologies. This research helps improve the accuracy of the WMM and contributes to the scientific community's broader understanding of the Earth's magnetic field and its various sources, from the core to electric currents in the near-Earth environment.
NCEI also participates in international initiatives, such as the International Association of Geomagnetism and Aeronomy (IAGA), to ensure the WMM reflects a global and cooperative approach to understanding and predicting changes in the Earth's magnetic field.
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