Evaluation of candidate models for the 13th generation International Geomagnetic Reference Field

Abstract In December 2019, the 13th revision of International Geomagnetic Reference Field (IGRF) was released by Association Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD. This comprises two new spherical harmonic main field models for epochs 2015.0 (DGRF-2015) 2020.0 (IGRF-2020) a model predicted secular variation interval to 2025.0 (SV-2020-2025). The were produced from candidates submitted fifteen international teams. These teams led British Geological Survey (UK), China Earthquake Administration (China), Universidad Complutense de Madrid (Spain), University Colorado Boulder (USA), Technical Denmark (Denmark), GFZ German Research Centre Geosciences (Germany), Institut physique du globe Paris (France), des Sciences la Terre Pushkov Institute Terrestrial Magnetism, Ionosphere Radio Wave Propagation (Russia), Kyoto (Japan), Leeds Max Planck Solar System NASA Goddard Space Flight Center Potsdam Université Strasbourg (France). candidate evaluated individually compared all other as well mean, median robust Huber-weighted candidates. analyses used identify, example, between Gauss coefficients or geographical regions where strongly differed. majority sufficiently close that differences can be explained primarily individual modeling methodologies data selection strategies. None so different warrant their exclusion final IGRF-13. IAGA V-MOD task force thus voted approaches: DGRF-2015 IGRF-2020 predictive SV-2020-2025. this paper, we document evaluation provide details approach derive IGRF-13 products. We also perform retrospective analysis IGRF-12 SV over performance period (2015–2020). Our findings suggest forecasting benefit combining physics-based core with satellite observations.