The International Geomagnetic Reference Field (IGRF) is a standard mathematical description of the Earth's main magnetic field. It is used widely in studies of the Earth's deep interior, crust, ionosphere, and magnetosphere. While this web page is hosted at NOAA/NCEI, the model itself is developed and maintained by the International Association of Geomagnetism and Aeronomy (IAGA).
13th Generation Release
The coefficients for the 13th generation of IGRF model were finalized by an IAGA task force in December 2019. The IGRF is the product of a collaborative effort between magnetic field modelers and the institutes involved in collecting and disseminating magnetic field data collected from satellites, observatories, and surveys around the world. Please review the Model Health Warning before using the IGRF.
Citation
International Geomagnetic Reference Field: the 13th generation, Alken, P., Thébault, E., Beggan, C.D. et al. International Geomagnetic Reference Field: the thirteenth generation. Earth Planets Space 73, 49 (2021). doi: 10.1186/s40623-020-01288-x
Access Methods
Data, Programs, and Software
NCEI provides access to IGRF 13 coefficients, as well as programs with the coefficients integrated into the source code.
- Coefficients: Text File | Spreadsheet
- Geomag 7.0 Software: Windows | Linux Tar File
- Python 3.7 Package
- Fortran Program (provided by the British Geological Survey)
IGRF 13 Calculators
NCEI and the British Geological Survey (BGS) created calculators to compute values for the geomagnetic field and secular variation for specific dates and coordinates.
Geomag 7.0 License and Copyright Information
The software code is in the public domain and not licensed or under copyright. The information and software may be used freely by the public. As required by 17 U.S.C. 403, third parties producing copyrighted works consisting predominantly of the material produced by U.S. government agencies must provide notice with such work(s) identifying the U.S. Government material incorporated and stating that such material is not subject to copyright protection.
Older versions of the IGRF may be required in special cases. For example, if a magnetic survey was conducted in 1983, the appropriate predictive IGRF-3 (available at that time) would have been subtracted to make an anomaly map. If the original data are no longer available to update the map, add the IGRF-3 to the anomaly map and then subtract IGRF-13 which includes the required definitive magnetic reference field (DGRF) model for 1980–1985.
| Model | Main Field | Secular Variation | Release Year |
|---|---|---|---|
| IGRF-1 | 1965.0 | 1975.0–1980.0 | 1965 |
| IGRF-2 | 1965.0–1975.0 | 1980.0–1985.0 | 1975 |
| IGRF-3 | 1965.0–1980.0 | 1980.0–1985.0 | 1980 |
| IGRF-4 | 1945.0–1985.0 | 1985.0–1990.0 | 1985 |
| IGRF-5 | 1945.0–1985.0 | 1985.0–1990.0 | 1987 |
| IGRF-6 | 1945.0–1990.0 | 1990.0–1995.0 | 1991 |
| IGRF-7 | 1900.0–1995.0 | 1995.0–2000.0 | 1995 |
| IGRF-8 | 1900.0–2000.0 | 2000.0–2005.0 | 2000 |
| IGRF-9 | 1900.0–2000.0 | 2000.0–2005.0 | 2003 |
| IGRF-10 | 1900.0–2005.0 | 2005.0–2010.0 | 2005 |
| IGRF-11 | 1900.0–2010.0 | 2010.0–2015.0 | 2010 |
| IGRF-12 | 1900.0–2015.0 | 2015.0–2020.0 | 2015 |
| IGRF-13 | 1900.0–2020.0 | 2020.0–2025.0 | 2020 |
Specifications
The IGRF is a series of mathematical models of the Earth's main field and its annual rate of change (secular variation). In source-free regions at the Earth's surface and above, the main field, with sources internal to the Earth, is the negative gradient of a scalar potential V which can be represented by a truncated series expansion:
Here, a = 6371.2 km and the degree of truncation is N = 13. The 13th Generation IGRF coefficients were computed from candidate sets of coefficients produced by the participating members of IAGA Working Group V-MOD. Their institutes and the many organizations involved in operating magnetic survey satellites, observatories, magnetic survey programs and World Data Centers are to be thanked for their continuing support of the IGRF project.
Magnetic Repeat Stations Survey
Activities
- Maintain a catalog of regional and global magnetic surveys, models and charts.
- Promote and set standards for magnetic repeat station surveys and reporting:
- Define reporting procedures and classification standards
- Encourage agencies to submit repeat data in appropriate formats to WDC, Boulder
- Maintain a catalog of national repeat station network descriptions
- Promote international interest in surveying, modeling and analysis of the internal geomagnetic field, both globally and on a regional scale.
| Countries contacted (no. organisations if > 1) | Response | Observatories | Current status of absolute observation network |
|---|---|---|---|
| ALBANIA | Yes | 0 | 10 repeat stations occupied 1994-1996 with assistance from Italy |
| ALGERIA | 1 | ||
| ANGOLA | 0 | ||
| ARGENTINA | 3 | ||
| AUSTRALIA | Yes | 8 | 15 repeat stations occupied every 1-2 years |
| AUSTRIA | 1 | ||
| BELGIUM | 2 | ||
| BOLIVIA | 1 | ||
| BOTSWANA | Yes | 0 | 5 repeat stations occupied in 1998-2000 with assistance from South Africa |
| BRAZIL | 2 | ||
| BULGARIA | 1 | ||
| CANADA | Yes | 12 | 5 primary repeat stations occupied every 2 years, 7 secondary stations occupied every 3-4 years and 2 tertiary stations whenever possible |
| CHINA (2) | 18 | ||
| COLOMBIA | Yes | 1 | ~ 80 stations at least every 5 years |
| COSTA RICA | 1 | ||
| CROATIA | Yes | 0 | no network but plans to establish 1-2 stations |
| CUBA | Yes | 1 | ~35 stations occupied whenever possible |
| CZECH REPUBLIC | Yes | 1 | 6 repeat stations occupied every 2 years |
| DENMARK | Yes | 4 | no network |
| DOMINION REPUBLIC OF CONGO | 0 | ||
| EGYPT | 1 | ||
| ESTONIA | Yes | 0 | no network |
| ETHIOPIA | Yes | 1 | no network |
| FINLAND (2) | Yes | 2 | 4 pulsation stations, at least one absolute |
| FRANCE | Yes | 1 | 33 repeat stations occupied every 5 years |
| FRANCE – OVERSEAS | Yes | 7 | 4 stations occupied in Antarctic and sub-Antarctic islands whenever possible |
| GEORGIA | Yes | 1 | 13-station network lapsed |
| GERMANY (2) | Yes | 3 | ~40 repeat stations occupied every 4 years |
| GREECE | Yes | 1 | 100 stations occupied by the military – data published as D chart only |
| HUNGARY (2) | Yes | 2 | 195 stations occupied in 1994-5. Plans to occupy 20 primary stations every 5 years and remaining secondary stations every 15 years. |
| ICELAND | Yes | 1 | 3 repeat stations occupied every 1-4 years |
| INDIA (3) | Yes | 10 | no network |
| INDONESIA | Yes | 2 | 53 stations occupied 1994-6, plans to resurvey every 5 years, Australia assisting |
| IRAN | Yes | 0 | no vector observations, intermittent F observations at Tehran observatory |
| IRAQ | 0 | ||
| IRELAND | Yes | 1 | 9 stations occupied in 1995 |
| ISRAEL | Yes | 1 | 3 repeat stations occupied every 3-5 years |
| ITALY | Yes | 3 | 8 repeat stations occupied in 1998, ~2500 vector observations 1977-82 |
| JAPAN (4) | Yes | 8 | 12 repeat stations occupied every 5 years (Maritime Safety Agency) and ~100 repeat stations occupied at a rate of ~3/year (Geographical Survey Institute) |
| KAZAKHSTAN | Yes | 1 | no network |
| KENYA | Yes | 0 | no network |
| KOREA | Yes | 0 | F observations at 4 sites |
| LUXEMBURG | 0 | ||
| MADAGASCAR | 1 | ||
| MALAWI | Yes | 0 | no network |
| MALAYSIA | Yes | 0 | no network |
| MEXICO | 1 | ||
| MONGOLIA | 0 | ||
| MOROCCO | 0 | ||
| MOZAMBIQUE | Yes | 1 | network lapsed |
| NEW ZEALAND | Yes | 3 | 30 repeat stations occupied every 3 years |
| NIGERIA | Yes | 0 | no network |
| NORWAY (2) | 4 | ||
| PAKISTAN (2) | Yes | 2 | no network |
| PAPUA NEW GUINEA | 0 | ||
| PERU | Yes | 2 | 7 stations occupied 1992-3 as part of International Equatorial Electrojet Year |
| PHILIPPINES | 0 | ||
| POLAND | 3 | ||
| PORTUGAL | Yes | 1 | no network |
| ROMANIA | Yes | 1 | 28 repeat stations occupied every 5 years |
| RUSSIA (3) | Yes | 14 | network lapsed |
| SLOVAK REPUBLIC | Yes | 1 | 12 repeat stations occupied every 2 years |
| SLOVENIA | 0 | ||
| SOUTH AFRICA | Yes | 3 | 63 repeat stations occupied every 5 years |
| SPAIN (3) | Yes | 5 | 40 repeat stations occupied every 3 years |
| SUDAN | 0 | ||
| SWEDEN (2) | 4 | ||
| SWITZERLAND | 0 | ||
| TAIWAN, REPUBLIC OF CHINA | 1 | ||
| TANZANIA | 0 | ||
| THAILAND | Yes | 0 | ~15 repeat stations occupied in 1996 |
| TUNISIA | 0 | ||
| TURKEY (2) | 1 | 85 repeat stations occupied every 5 years, data confidential | |
| U.K. | Yes | 6 | 51 repeat stations occupied every 3-5 years |
| U.S.A. | Yes | 13 | 24 repeat stations occupied every 3-5 years |
| UKRAINE | Yes | 4 | network lapsed |
| VENEZUALA | 0 | ||
| VIETNAM | Yes | 1 | 56 repeat stations occupied every 6 years |
| YUGOSLAVIA | Yes | 1 | 5 repeat stations occupied every 3 years |
| ZAMBIA | Yes | 0 | no network |
| ZIMBABWE | 0 |
