The 14th Generation of the International Geomagnetic Reference Field

The 14^th generation of the International Geomagnetic Reference Field (IGRF-14) was officially released in November 2024. It is valid from 1900.0 to 2030.0 and supersedes the 13^th generation IGRF, which ends at 2025.0. The IGRF-14 model consists of five-yearly snapshots of the magnetic field represented by Gauss coefficients. The main magnetic field is captured up to spherical harmonic degree and order 13.

In this generation, the coefficients for 2020.0 have been updated and are now definitive, and new coefficients for 2025.0 have been computed. An estimate of the secular variation (to degree and order 8) for the next five years, from 2025.0 until 2030.0, has also been created.

Creating the IGRF-14 was a truly international effort involving data from global geomagnetic observatories and multiple satellite missions, including ESA Swarm and Macau Scientific Satellite-1 (MSS-1). The initial call for candidates was released in March 2024, and the final candidates were submitted in October. We received candidate models from 19 different institutions worldwide, some of whom had not previously submitted IGRF candidates. For comparison, the number of teams that submitted candidates was 10 for IGRF-12 (released in 2015) and 15 for IGRF-13 (released in 2020), reflecting the growing community and the importance of geomagnetism.

For this generation, a GitHub repository was established to maintain an open record of the submission and analysis process for the candidate models. To evaluate the candidates and decide how best to combine these submitted models into the final IGRF14 coefficients, a volunteer group of experts was established to make independent recommendations.

In this talk, we describe the candidate models, provide details of the standard analysis of magnetic field models performed, and show how research software engineering tools, such as the IGRF14 GitHub repository, were used to automatically generate an evaluation of each submitted candidate. We discuss the evaluation process and how the final IGRF14 coefficients were agreed upon. We document some of the new features in the latest magnetic field maps.