Federal government websites often end in. The site is secure. We apologize for any inconvenience. It is used widely in studies of the Earth's deep interior, crust, ionosphere, and magnetosphere.
The IGRF is the product of a collaborative effort between magnetic field modelers and the institutes involved in collecting and disseminating magnetic field data collected from satellites, observatories, and surveys around the world.
International Geomagnetic Reference Field: the thirteenth generation. Earth Planets Space 73, 49 Related Articles. NCEI Calculator. BGS Calculator. The software code is in the public domain and not licensed or under copyright. The information and software may be used freely by the public. As required by 17 U. Government material incorporated and stating that such material is not subject to copyright protection. Older versions of the IGRF may be required in special cases.
For example, if a magnetic survey was conducted in , the appropriate predictive IGRF-3 available at that time would have been subtracted to make an anomaly map.
The IGRF is a series of mathematical models of the Earth's main field and its annual rate of change secular variation. In source-free regions at the Earth's surface and above, the main field, with sources internal to the Earth, is the negative gradient of a scalar potential V which can be represented by a truncated series expansion:.
