World Magnetic Model (WMM)
The World Magnetic Model (WMM) is a vital geomagnetic reference used by the U.S. Department of Defense, NATO, and many civilian navigation systems. The WMM helps determine the direction of magnetic north and is essential for satellite navigation, smartphone orientation, and aviation systems.
Earth’s magnetic field is constantly changing due to dynamic processes in the planet’s outer core. These changes can affect compass-based navigation systems and require regular updates to magnetic models. The WMM is updated every five years and provides accurate magnetic declination data globally.
The latest WMM release improves forecasting and accounts for recent anomalies such as the accelerated movement of the magnetic north pole. Scientists from NOAA and the British Geological Survey maintain and calibrate the model using data from satellites like Swarm and ground observatories.
In addition to traditional use in military and aviation navigation, WMM data supports numerous commercial applications — including smartphone compass calibration, geological surveys, and autonomous vehicle positioning systems.
For researchers and developers, the model’s parameters and source code are publicly available and widely implemented in software and navigation devices worldwide.
The World Magnetic Model helps people know where magnetic north is. It’s used in everything from smartphones and car navigation systems to airplanes and satellites. Earth’s magnetic field slowly changes over time, so the model is updated every five years to keep things accurate.
Just like a compass needle moves, so does magnetic north—this model keeps digital systems pointed in the right direction.
The World Magnetic Model (WMM) is a mathematical representation of Earth’s large-scale magnetic field. It is based on a spherical harmonic expansion up to degree and order 12 and incorporates real-time data from satellites such as Swarm, as well as ground-based observatories. The model provides values for geomagnetic field components including declination, inclination, and total intensity at any location on Earth.
Regular updates are required due to secular variation—caused by fluid motion in Earth’s outer core—which alters magnetic field lines. The WMM is critical to navigation systems, inertial guidance, and space weather forecasting.
