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International Geomagnetic Reference Field (IGRF)

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).

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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

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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. 

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.

Older Versions of IGRF
ModelMain FieldSecular VariationRelease Year
IGRF-11965.01975.0–1980.01965
IGRF-21965.0–1975.01980.0–1985.01975
IGRF-31965.0–1980.01980.0–1985.01980
IGRF-41945.0–1985.01985.0–1990.01985
IGRF-51945.0–1985.01985.0–1990.01987
IGRF-61945.0–1990.01990.0–1995.01991
IGRF-71900.0–1995.01995.0–2000.01995
IGRF-81900.0–2000.02000.0–2005.02000
IGRF-91900.0–2000.02000.0–2005.02003
IGRF-101900.0–2005.02005.0–2010.02005
IGRF-111900.0–2010.02010.0–2015.02010
IGRF-121900.0–2015.02015.0–2020.02015
IGRF-131900.0–2020.02020.0–2025.02020

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:

Image contains the following equation:{\displaystyle V(r,\phi ,\theta ,t)=a\sum _{\ell =1}^{L}\sum _{m=0}^{\ell }\left({\frac {a}{r}}\right)^{\ell +1}\left(g_{\ell }^{m}(t)\cos m\phi +h_{\ell }^{m}(t)\sin m\phi \right)P_{\ell }^{m}\left(\cos \theta \right)}

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.

Regional Magnetic Survey Results
Countries contacted (no. organisations if > 1)ResponseObservatoriesCurrent status of absolute observation network
ALBANIAYes010 repeat stations occupied 1994-1996 with assistance from Italy
ALGERIA 1 
ANGOLA 0 
ARGENTINA 3 
AUSTRALIAYes815 repeat stations occupied every 1-2 years
AUSTRIA 1 
BELGIUM 2 
BOLIVIA 1 
BOTSWANAYes05 repeat stations occupied in 1998-2000 with assistance from South Africa
BRAZIL 2 
BULGARIA 1 
CANADAYes125 primary repeat stations occupied every 2 years, 7 secondary stations occupied every 3-4 years and 2 tertiary stations whenever possible
CHINA (2) 18 
COLOMBIAYes1~ 80 stations at least every 5 years
COSTA RICA 1 
CROATIAYes0no network but plans to establish 1-2 stations
CUBAYes1~35 stations occupied whenever possible
CZECH REPUBLICYes16 repeat stations occupied every 2 years
DENMARKYes4no network
DOMINION REPUBLIC OF CONGO 0 
EGYPT 1 
ESTONIAYes0no network
ETHIOPIAYes1no network
FINLAND (2)Yes24 pulsation stations, at least one absolute
FRANCEYes133 repeat stations occupied every 5 years
FRANCE – OVERSEASYes74 stations occupied in Antarctic and sub-Antarctic islands whenever possible
GEORGIAYes113-station network lapsed
GERMANY (2)Yes3~40 repeat stations occupied every 4 years
GREECEYes1100 stations occupied by the military – data published as D chart only
HUNGARY (2)Yes2195 stations occupied in 1994-5. Plans to occupy 20 primary stations every 5 years and remaining secondary stations every 15 years.
ICELANDYes13 repeat stations occupied every 1-4 years
INDIA (3)Yes10no network
INDONESIAYes253 stations occupied 1994-6, plans to resurvey every 5 years, Australia assisting
IRANYes0no vector observations, intermittent F observations at Tehran observatory
IRAQ 0 
IRELANDYes19 stations occupied in 1995
ISRAELYes13 repeat stations occupied every 3-5 years
ITALYYes38 repeat stations occupied in 1998, ~2500 vector observations 1977-82
JAPAN (4)Yes812 repeat stations occupied every 5 years (Maritime Safety Agency) and ~100 repeat stations occupied at a rate of ~3/year (Geographical Survey Institute)
KAZAKHSTANYes1no network
KENYAYes0no network
KOREAYes0F observations at 4 sites
LUXEMBURG 0 
MADAGASCAR 1 
MALAWIYes0no network
MALAYSIAYes0no network
MEXICO 1 
MONGOLIA 0 
MOROCCO 0 
MOZAMBIQUEYes1network lapsed
NEW ZEALANDYes330 repeat stations occupied every 3 years
NIGERIAYes0no network
NORWAY (2) 4 
PAKISTAN (2)Yes2no network
PAPUA NEW GUINEA 0 
PERUYes27 stations occupied 1992-3 as part of International Equatorial Electrojet Year
PHILIPPINES 0 
POLAND 3 
PORTUGALYes1no network
ROMANIAYes128 repeat stations occupied every 5 years
RUSSIA (3)Yes14network lapsed
SLOVAK REPUBLICYes112 repeat stations occupied every 2 years
SLOVENIA 0 
SOUTH AFRICAYes363 repeat stations occupied every 5 years
SPAIN (3)Yes540 repeat stations occupied every 3 years
SUDAN 0 
SWEDEN (2) 4 
SWITZERLAND 0 
TAIWAN, REPUBLIC OF CHINA 1 
TANZANIA 0 
THAILANDYes0~15 repeat stations occupied in 1996
TUNISIA 0 
TURKEY (2) 185 repeat stations occupied every 5 years, data confidential
U.K.Yes651 repeat stations occupied every 3-5 years
U.S.A.Yes1324 repeat stations occupied every 3-5 years
UKRAINEYes4network lapsed
VENEZUALA 0 
VIETNAMYes156 repeat stations occupied every 6 years
YUGOSLAVIAYes15 repeat stations occupied every 3 years
ZAMBIAYes0no network
ZIMBABWE 0