(Guest post Summarized by Hirokuni Oda)
Special issue “International Geomagnetic Reference Field—the twelfth generation” was published as one of the thematic series of SpringerOpen journal “Earth, Planets and Space” (EPS). This special issue synthesizes the efforts made during the construction of the twelfth generation of the International Geomagnetic Reference Field (IGRF-12) that was released online in December 2014 (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html). The IGRF-12 is a series of standard mathematical models describing the large scale internal part of the Earth’s magnetic field between epochs 1900.0 and 2015.0 with a forecast to epoch 2020.0. This activity has been maintained since 1968 by a working group of volunteer scientists from several international institutions but grew out from discussions started in the early 1960s (Barton, 1997). The IGRF task force operates under the auspices of the International Association of Geomagnetism and Aeronomy (IAGA), which is one of the International Union of Geodesy and Geophysics (IUGG). The twelfth generation of IGRF models extends and updates the previous one (the IGRF-11, Finlay et al., 2010). It provides a new Definitive Geomagnetic Reference Field model for epoch 2010.0. It proposes a provisional reference field model for epoch 2015.0 and a predictive part for epochs ranging from 2015.0 to 2020.0 (Thébault et al. [2015a]). These models were derived from candidate models submitted by 10 teams worldwide. Modelers made use of the data measured at ground geomagnetic observatories and built their models using satellite data from CHAMP (2000–2010), Ørsted (1999-), SAC-C (2001–2013), and the Swarm constellation (launched in November 2013; see also, Friis-Christensen and Floberghagen, 2013). The evaluation procedure and the applied diagnostic tests are documented in Thébault et al. (2015). Users may obtain the IGRF-12 model coefficients in electronic form, software for evaluating the model, and a “health warning” concerning the use of IGRF-12, online at http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html.