Secular variation

Magnetic field

Ionosphere

Physics

Declination

Geology

Astronomy

Geodesy

Stars

Aeronomy

Earth's magnetic field

Pure mathematics

Epoch (astronomy)

Mathematics

Magnetic declination

Quantum mechanics

Geophysics

Field (mathematics)

Earth Planets and Space

In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group (V-MOD) adopted the thirteenth generation of the International Geomagnetic Reference Field (IGRF). This IGRF updates the previous generation with a definitive main field model for epoch 2015.0, a main field model for epoch 2020.0, and a predictive linear secular variation for 2020.0 to 2025.0. This letter provides the equations defining the IGRF, the spherical harmonic coefficients for this thirteenth generation model, maps of magnetic declination, inclination and total field intensity for the epoch 2020.0, and maps of their predicted rate of change for the 2020.0 to 2025.0 time period.

International Geomagnetic Reference Field: the thirteenth generation