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 14th 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
- 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) | Response | Obser-vatories | 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 |