The problem with IGRF commercialization



I wish to comment on the news item, “Geomagnetic Reference Field: To License or Not to License?,” by Stuart and others, which appeared in the February 19 issue of Eos. It is important to recall some of the history of establishing an International Geomagnetic Reference Field (IGRF) and the conditions that prevailed before the field was standardized. Before the IGRF most magnetic total field data were reduced to anomalies by many different procedures, sometimes known only to the author. A true “Tower of Babel” existed. To correct this situation, international researchers conducted a great deal of work (see World Magnetic Survey, IAGA Bulletin No. 28, edited by Alfred J. Zmuda, 1971), which culminated in the IAGA Symposium on the Description of the Earth's Magnetic Field, held in October, 1968 in Washington, D.C. This meeting established the IGRF and subsequently the reference field was adopted by the international community of geomagneticians. At last when magnetic anomaly fields were published the author would state that the IGRF 1965.0 was removed; and the reader would know precisely what was removed from the total field measurements. Later, larger regional magnetic anomaly maps could be made more easily from smaller surveys, since the reference level removed was known. Unfortunately, there have been problems with accurate secular variation terms, which has necessitated a DGRF and other variations. The main success of the IGRF, however, has been that when data are reduced with this known field model, others are aware of precisely what was removed from the total intensity field to produce the anomaly map. Therefore, it is essential that an international standard reference field be maintained.