The International Geomagnetic Reference Field 2005

The International Geomagnetic Reference Field (IGRF) is a spherical harmonic model of the Earth’s magnetic field and its components based on data collected from magnetic observatories and satellite-based data collection. The IGRF 2005 is valid for the years 2005–10.

The IGRF 2005 is represented as a series of charts showing the main field (total intensity), vertical component, horizontal component, inclination, and declination, as well as the secular variation (annual change) of each component.

Courtesy of U.S. Geological Survey.