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Geomagnetic Utility Programs

NCEI provides access to 12 programs (described and referenced in Introduction to Geomagnetic Fields by Wallace Campbell) that are designed to help users understand geomagnetic fields. These programs are all designed to operate in a DOS environment, with a few exceptions:

  • GEOMAG will run in a DOS window within a Windows PC environment, but will not execute in a pure 16-bit DOS environment
  • DSTDEMO may not execute from Windows 2000 DOS prompts

GMCORD, Day Number, POLYFIT, SORTVAL and ANALYZ are available in both Linux and Windows with C source code. A new program GMPOLE is also available in this fashion.

Disclaimer: These programs are intended as educational tools to help users understand geomagnetic fields, and are free to access and share without restriction. They are not guaranteed or intended for any other purpose. Neither NCEI nor the book publishers provide a warranty (expressed or implied), endorsement, guarantee of accuracy, or responsibility for the program's functioning. The executable programs (.exe) and all other necessary files must also be copied to the same directory for proper operation of the set.


Note: Google and Mozilla have deprecated support for FTP server access on Chrome and Firefox. Review the documentation to learn about FTP access options.

FTP Documentation

Geomagnetic Field Programs
Program Name Description Download Options


Mean, Standard Deviation, and Correlation | ANALYZ Documentation


A file processing program for geomagnetic coordinate transformation | APEX Documentation

Day Number

Determines the number of the day in the year | Day Number Documentation


Geomagnetic Disturbance Index, demonstration of spherical harmonics | DSTDEMO Documentation

Program and data (ftp)


Computes the Fourier harmonic spectral components of quiet field records | FOURSQ1 Documentation

Program (ftp)


Provides field values computed from the International Geomagnetic Reference Field (IGRF) model | IGRF Fields Documentation

Program and data (ftp)


Performs coordinate transformation from Geodetic to Geomagnetic coordinates | GMCORD Documentation


Location of the North Geomagnetic Pole | GMPOLE Documentation

IGRF Field Models

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) for 1900–2005. | IGRF Model Fields Documentation

Table (ftp)


Creates a polynomial equation portrayal of data points | POLYFIT Documentation


Median of sorted values | SORTVAL Documentation


Graphical demonstration of Spherical Harmonics | SPH Documentation

Program (ftp)


Quiet-Day Field Variation, Sq | SQU1MODEL Documentation

Program (ftp) 


Location of the Sun and Moon | SUN-MOON Documentation

Program (ftp)

Utility C Programs 

A package of all the new C utility programs