Evidence-based uncertainty estimates for the International Geomagnetic Reference Field

Abstract The International Geomagnetic Reference Field (IGRF) is a multi-institute model of the Earth’s magnetic field, compactly described by sets up to 195 spherical harmonic (Gauss) coefficients degree and order 13, which allows continuous evaluation field at any location time on or above surface. It developed from satellite ground-based magnetometer data describes large-scale variation in space under quiet conditions. While much effort has been made improving forecast secular over 5-year intervals between release renewal, less emphasis placed understanding spatial errors user point view. In this study, we estimate time-invariant uncertainty IGRF based globally averaged misfit measurements repeat stations observatories 1980 2021. As ground are reduced quiet-time values, external minimized for purposes study. We find 68.3% confidence interval 87 nT North (X) component, 73 East (Y) component 114 vertical (Z) component. Due Laplacian distribution residuals, standard deviations larger 144, 136 293 nT, respectively. Graphical