NOAA Logo, NOAA Satellites and Information, National Geophysical Data Center (NGDC).

Geomag top navigation banner
Links to related web resources go to NOAA's Space Weather prediction Center Now DoD World Magnetic Model Home Links and descriptions of magnetic field models and software go to the Geomagnetic Data Home go to all data and information Answers to Frequently Asked Questions Go to the Space Physics Interactive Data Resource Geomagnetic Data online at NGDC

Geomagnetic Models and Software

NGDC-720: September 2006 release of version 1.0 crustal magnetic field model. A convenient way of representing geomagnetic fields is to expand the scalar magnetic potential into spherical harmonic functions that can then be evaluated at any desired location to provide the magnetic field vector, its direction, or the anomaly of the total intensity of the field. The NGDC-720 model provides such an expansion for the crustal field from spherical harmonic degree 16 to 720, corresponding to the waveband of 2500 km to 56 km. The degree 720 cut-off corresponds to an angular wavelength of 30 arc minutes, providing a 15 arc minute model resolution.

NewRevised on-line calculators for the IGRF (1900-2010), DoD WMM (2005-2010), Declination only (1900-2010), US Historic Declination (1750-2010)

New IAGA Web Image Spreadsheet Tool - display and download IAGA magnetic field maps and data from 1900 - 2005. The Wist allows the user to select the number of rows (years) and columns (magnetic elements) to display. Each "cell" of the Wist displays the appropriate map for the selected year and element and links to the PDF for a higher resolution version of the map and to the data used to create the map.

The Epoch 2005-2010 Models
Because the Earth's magnetic field is constantly changing, it is impossible to accurately predict what the field will be at any point in the very distant future. By constantly measuring the magnetic field, we can observe how the field is changing over a period of years. Using this information, it is possible to create a mathematical representation of the Earth's main magnetic field and how it is changing. Since the field changes the way it is changing, new observations must continually be made and models generated to accurately represent the magnetic field as it is. NGDC participates in the development and distribution of two global main-field models, the World Magnetic Model and the International Geomagnetic Reference Field Model. The WMM is the standard navigation model for the U.S. and U.K. Departments of Defense and NATA. The IGRF is the international research reference model.

Note: To learn more about these models, visit the home Web sites for the US / UK World Magnetic Model (WMM) 2005 and IAGA IGRF-10 .

NGDC distributes two main magnetic field models, the International Association of Geomagnetism and Aeronomy (IAGA) International Geomagnetic Reference Field (IGRF) model and the Department of Defense (DoD) World Magnetic Model (WMM). You can download the models for use on your own machine, or compute magnetic field values online from the current IGRF model. Before using the IGRF please look at the 'Health Warning'.

  • New Download the current NGDC GEOMAG Version 6.1 (02/2008) software ( Windows zip exe or Linux tar file, containing the C software, model and readme file) including both the IGRF and WMM model.
  • Download IAGA's current International Geomagnetic Reference Field (IGRF)
    • Visit the IAGA Web to learn more about the IGRF.
  • In addition to the standard model products, NGDC, in collaboration with the Colorado Institute for Research in the Environmental Sciences (CIRES), has several research products available. To learn more about the CIRES/NGDC geomagnetic research efforts, visit the CIRES Geomagnetism Web site.
  • Download the collection of Utility Programs including (partial list):
    GMCORD program which determines the geomagnetic coordinates for any selected global location.
    SQ1MODEL program which produces an estimate of the daily variation of field for any global location
    DSTDEMO program illustrates the change of the DST mid-latitude fields during a storm
    SUNMOON program gives the position of the Sun and Moon for any observer latitude, longitude and selected time
  • Access to the Auroral Electrojet Index, AE
  • Forecast information on magnetic storms is available through the NOAA Space Environment Center, or through NOAA's recorded message service at 303-497-3235.