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Northern Hemisphere Total Magnetic Field

Total magnetic field viewed from above the northern hemisphere.

Utility Programs for Geomagnetic Fields

Below are links to descriptions of the 12 computer program files, mentioned in the book Introduction to Geomagnetic Fields by Wallace Campbell (Cambridge University Press 2nd Ed. 2003). The executable files are all designed to operate in a DOS environment. However, the program, GEOMAG, will run in a DOS window within a Windows PC environment, but will not execute in a pure 16-bit DOS environment. The program, DSTDEMO, may not execute from Windows 2000 DOS prompts. We apologize for any difficulties this may cause.

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.

The executable files are designed for a DOS compatible, personal computer. The programs were designed to assist the user in understanding the subject of geomagnetic fields; no claim is made regarding the suitability of the software for any other purpose. No restriction has been placed on the sharing of these programs; also, no warranty (expressed or implied), no endorsement, no guarantee of accuracy, and no responsibility for the program's functioning, can be made by the program authors, the author or publisher of this book, or by the National Geophysical Data Center. The executable programs (.exe) and all other necessary files must also be copied to the same directory for proper operation of the set.


The programs and associated data files are available from the National Geophysical Data Center FTP directory /geomag/Utilities/ or, at a nominal charge, on 1.44 Mbyte diskette (see contact information below). When downloading programs using a Web browser, files of type "exe" will automatically bring up a "Save As" window. Associated data and text files (i.e. files of type "txt" and "dat") will open in your browser window. To save text type files from your browser window to your local machine, choose "FILE" and "Save As" from your browser task bar. From the program description page, a download link is provided to the individual program, or in the case of a program requiring data file(s), the link is to a self-extracting zip file which contains the program and all associated files.

  1. GMCORD - Performs coordinate transformation from Geodetic to Geomagnetic coordinates
  2. GEOMAG - provides field values computed from the International Geomagnetic Reference Field (IGRF) model
  3. SQ1MODEL - Quiet-Day Field Variation, Sq
  4. DSTDEMO - Geomagnetic Disturbance Index, Dst
  5. SUN-MOON - Location of the Sun and Moon
  6. Day Number - determines the number of the day in the year
  7. POLYFIT - creates a polynomial equation portrayal of data points
  8. FOURSQ1 - computes the Fourier harmonic spectral components of quiet field records
  9. SORTVAL - Median of Sorted Values
  10. ANALYZ - Mean, Standard Deviation, and Correlation
  11. SPH - Graphical demonstration of Spherical Harmonics
  12. Table of all IGRF Models
  13. GMPOLE - Location of the North Geomagnetic Pole.
  14. A package of all the new C utility programs Linux Windows
  15. APEX - A file processing program for geomagnetic coordinate transformation.