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12. Table of All Field ModelsThe ALLIGRF.TAB file is a table of all the spherical harmonic Gauss coefficients, g and h, of the International Geomagnetic Reference Fields (IGRF) and Definitive Geomagnetic Reference Fields (DGRF) to cover the years from 1900 to 2005. This table was adopted by the Working Group 8 of IAGA Division V. For each fiveyear epoch (column) the g and h Gauss coefficients (in nanotesla units) are given (in ordered rows) up to values of degree (n) 10 and order (m) 10. The SV column to the right represents the secular variation in units of nanotesla (gamma) per year and is used to extend the 2000 epoch values to the year 2005. These coefficients are used to determine the geomagnetic potential function V (from which the XYZ or HDZ field component values are derived) with the formulation where a is the mean Earth radius, r is the radial distance from the center of the Earth, f is the longitude measured eastward from Greenwich, ? is the geocentric colatitude, and Pmn is the Schmidtnormalized associated Legendre polynomial of degree n and order m. The maximum number of n is N (N=10 in the table) and m is less than or equal to n. Download this table (selfextracting zip file) Use your browser back button or the navigation bar at the top to return to the Geomagnetic Utility Programs Home. 
