Initial data, used for development of Atlas of Earth's Main
Magnetic Field (EMMF) from 1500 to 2010, can be divided in
five categories:
- Coefficient values of EMMF expansion in spherical
harmonics according to the Gauss method for the period of
1900–2005;
- Coefficient values of EMMF expansion in spherical
harmonics according to the Gauss method for the period of
1500–1900, obtained by modern computations;
- Coefficient values of EMMF expansion in spherical
harmonics according to the Gauss method for the period of
1500–1900, obtained in XIX century;
- Data of geomagnetic observations, obtained in 1500–1900;
- Historical world charts of geomagnetic field components,
developed in 1500–1900.
The first category is related to the International Geomagnetic
Reference Field's (IGRF) data of the International Association
of Geomagnetism and Aeronomy (IAGA). The second refers
to coefficients, obtained in the framework of several modern
approaches to modeling historical EMMF, adopted by the world
scientific geomagnetic community. The third – to coefficients,
calculated by the founder of the method of EMMF expansion in
spherical harmonics K. F. Gauss and some of his contemporaries.
The fourth deals with historical geomagnetic observations' data
of 1500–1900, accumulated into a single data massif over 20 years
by many researchers of the entire world, representing as
of to date the most complete collection of such data. The
fifth category relates to historical world charts of geomagnetic
field components, elaborated by navigators and scientists during
1500–1900: isogonic, isoclinic, isodynamic lines.