国际地磁学与高层大气物理学协会(IAG-A)于1968年采用了1965年国际地磁参考场(I-GRF 1965),这是第一个国际地磁参考场(In-ternational Geomagnetic Reference Field,缩写为 IGRF)。它是由1965.0年代的基本磁场模式和长期变化模式组成的,由于有了长期变化模式,故基本磁场模式可以向后和向前延伸使用,但是,不能早于1955.0或晚于1975.0。即:IGRF1965的有效使用期是1955.0—1975.0。后来,又采用了1975年国际地磁参考场(IGRF1975),它由延长使用到1975年的 The International Society for Geomagnetism and High Atmospheric Physics (IAG-A) adopted the 1965 International Geomagnetic Reference Field (I-GRF 1965) in 1968 as the first International Geomagnetic Reference Field For IGRF). It consists of a basic magnetic field pattern and a long-term variation pattern from the 1965’s and 0’s. Because of the long-term variation pattern, the basic magnetic pattern can be extended backwards and forwards, but it can not be earlier than 1955.0 or later than 1975.0. That is, the effective life of IGRF1965 is 1955.0-1975.0. Later, it adopted 1975 International Geomagnetic Reference Field (IGRF1975), which extended from the use of 1975