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International audienceThe eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.0–2015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examined

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.

S U M M A R YIn this paper the new GFZ Reference Internal Magnetic Model (GRIMM) is presented. The model has been derived from nearly 6 yr of CHAMP satellite data and 5 yr of observatory hourly means. At high latitudes, full vector satellite data are used at all local times which allows a separation between, on one hand, the fields generated by ionosphere and field aligned currents, and, on the other hand, the fields generated in the Earth's core and lithosphere. This selection technique leads to a data set without gaps during the polar summers resulting in a core field model that has an unprecedented time resolution. The modelled static core field, secular variation and lithospheric field are all in good agreement with previously published magnetic field models. Order five B-splines are used to model the variation in time of the core field. The energy in the secular acceleration has, therefore, a smooth behaviour in time and increases continuously from 2003.5. Mapping the field acceleration from 2001.5 to 2005.5 reveals its rapid and complex evolution over this time period at the Earth's surface. Due to the applied regularization technique, the acceleration energy in spherical harmonics 6-11 is significantly larger than for other models and we show that such a spectrum is acceptable.