Abstract:
The International Association of Geomagnetism and Aeronomy (IAGA) has released the 11th Generation International Geomagnetic Reference Field (IGRF) — the latest version of a standard mathematical description of the Earth's main magnetic field that is used widely in studies of the Earth's deep interior, its crust and its ionosphere and magnetosphere. The coefficients for this degree and order 13
... main field model were finalized by a task force of IAGA in December 2009. The IGRF is the product of a collaborative effort between magnetic field modellers and the institutes involved in collecting and disseminating magnetic field data from satellites and from observatories and surveys around the world.
The IGRF is a series of mathematical models of the Earth's main field and its annual rate of change (secular variation).
http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html 
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