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IGRF-14 is the fourteenth generation of the International Geomagnetic Reference Field (IGRF), a spherical harmonic model of Earth’s main magnetic field and its secular variation, developed through international collaboration under the auspices of the International Association of Geomagnetism and Aeronomy (IAGA). This paper describes the development, in October 2024, of candidate main field (MF) models at epochs 2020.0 and 2025.0, and a secular variation (SV) model at 2025.0, derived from Swarm satellite data, as well as the validation of the SV model using ground-based observatory measurements. Swarm data collected through May 2025 were subsequently used to update the continuous parent model from which these candidates were derived, which now spans 2014.42 to 2024.92. This model is used to conduct a retrospective assessment of SV performance and to analyze recent secular acceleration (SA) signals. Our results reveal a pronounced SA pulse centered in 2022 and provide evidence for a geomagnetic jerk in 2024, confirmed by recent observatory data from Western Europe and North America. These rapid, nonlinear core field changes have already contributed to the early degradation of the IGRF-14 SV forecast, underscoring the challenges of modeling geomagnetic field evolution and the importance of continuous satellite and ground-based observations. Graphical Abstract

Observations of the geomagnetic field taken at Earth’s surface and at satellite altitude are combined to construct continuous models of the geomagnetic field and its secular variation from 1957 to 2020. From these parent models, we derive candidate main field models for the epochs 2015 and 2020 to the 13th generation of the International Geomagnetic Reference Field (IGRF). The secular variation candidate model for the period 2020–2025 is derived from a forecast of the secular variation in 2022.5, which results from a multi-variate singular spectrum analysis of the secular variation from 1957 to 2020.

Continuous satellite measurements of the Earth's magnetic field have advanced the characterization of spatial‐temporal variations of the main field over the past two decades. To comprehend the underlying mechanism responsible for the geomagnetic field variations, we develop a novel core surface flow inversion scheme based on physics‐informed neural networks. The inversion method can account for the secular variation contributed by the interaction between the core flow and undetectable small‐scale magnetic fields. Based on the novel inversion framework, we derive a time‐dependent core surface flow model between 2000 and 2022 from the CHAOS‐7 core field model. The inverted core flow is then analyzed using the dynamic mode decomposition to extract wave‐like fluid motions. By calculating the magnetic secular acceleration contributed by each dynamic mode, we identify that the dynamic modes with period of about 10 and 7 years are responsible for geomagnetic jerks in the Atlantic and Pacific equatorial regions. Plain Language Summary Over the past two decades, satellites have been continuously monitoring the Earth's magnetic field. The major part of the field comes from the liquid part of the Earth's core. Geomagnetic measurements show quick changes in the field, including sudden shifts known as geomagnetic jerks. These shifts are believed to be linked to specific fluid motions in the Earth's core. Our study aims to better understand these flows and their effects. We use a method involving neural networks to figure out the patterns of flow at the core surface from the satellite data. We then use a technique to separate these flow patterns into simpler wave‐like forms. This helps us see how each wave pattern affects changes in the magnetic field. Our findings suggest that wave‐like motions with period of about 10 and 7 years caused geomagnetic jerks in the Atlantic and Pacific regions near the equator. Key Points A novel core surface flow inversion scheme based on physics‐informed neural networks is developed The inverted flow from the CHAOS‐7 model is analyzed using the dynamic mode decomposition to extract wave‐like flow patterns Geomagnetic jerks in the Atlantic and Pacific equator are related to two dynamic modes with period about 10 and 7 years

A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μ A / m 2 flowing on the sunlit side of the E-region ionosphere at about 90–150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the non-specialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

Measurements from low Earth orbit satellites play an important role in modern geomagnetic field modelling. In this study, we present two geomagnetic field models, WHUEMM-S, derived by sequential inversion, and WHUEMM-C, derived by comprehensive inversion. Both models are constructed from calibrated Swarm A/B, GRACE-FO 1, and CryoSat-2 observations collected between January 2019 and July 2024. Both models represent the core field with degree 15 spherical harmonics and temporal sixth order B-splines. This study assesses the impact of these inversion strategies and evaluates the value of non-dedicated satellites in geomagnetic field modelling. Power spectral analysis shows that both models produce a temporally stable main field (MF) energy and secular variation (SV) energy, with differences from CHAOS-7.18 of about 1 nT 2 and 1 (nT/year) 2 for spherical harmonic degrees below 6. Stronger regularization damping in WHUEMM causes a sharp decrease in secular acceleration (SA) at degrees above 7. WHUEMM-C departs from CHAOS-7.18 mainly in the axial dipole and a few low-order sectoral terms, whereas the high-degree misfits in WHUEMM-S are probably driven by spectral truncation and residual external signals. Global MF maps confirm that both models reproduce mid- and low-latitude features well; however, at high latitudes WHUEMM-S deviates more from CHAOS-7.18 than WHUEMM-C does. SV derived from observatory records confirm that each model maintains smooth temporal end points and reliably captures long-term trends. This demonstrates that carefully calibrated, non-dedicated data from GRACE-FO 1 and CryoSat-2 can be used to build global geomagnetic models without compromising robustness. Finally, using WHUEMM-S as the parent model, we produced and submitted three IGRF-14 candidate models. Graphical Abstract

Paleomagnetic studies typically assume that the long‐term, time‐averaged geomagnetic field behaves as a geocentric axial dipole (GAD). While paleodirectional data over the past five million years generally agree with GAD predictions, mid‐to‐low latitude paleointensity records fail to show GAD, with high values from Hawaii. Possible causes include experimental biases, non‐dipole field contributions, and uneven temporal sampling. In this study, we conduct alternating field and thermal demagnetization measurements, as well as paleointensity experiments, on 12 late Pleistocene (∼0.2–0.5 Ma) lava flows from northern Hainan Island (∼20°N, ∼110°E) of the Brunhes normal polarity chron. Eleven sites yield stable paleomagnetic directions (D = 9.1°, I = 24.3°, α95 = 4.0°), defining a virtual geomagnetic pole (VGP) at 78.7°N, 237.7°E, with VGP dispersion of 12.9°. Paleointensity results from four qualified sites range from 28.8 to 48.9 μT (mean = 37.8 ± 6.9 μT), which are in agreement with the Brunhes Hawaiian data from the same latitude. The directional and intensity results from Hainan are consistent with previous studies at similar latitudes but deviate from GAD predictions. Our results suggest that the high paleointensity values observed in the Hawaiian region may result from differences in age distributions compared with records from other latitudes. Considering these temporal differences, the observed non‐GAD characteristics at mid‐to‐low latitudes may partly reflect comparisons between time‐averaged field properties over distinct geological intervals.

The Carrington storm in 1859 September has been arguably identified as the greatest geomagnetic storm ever recorded. However, its exact magnitude and chronology remain controversial, while their source data have been derived from the Colaba H magnetometer in India. Here, we have located the Colaba 1859 yearbook, containing hourly measurements and spot measurements. We have reconstructed the Colaba geomagnetic disturbances in the horizontal component (ΔH), the eastward component (ΔY), and the vertical component (ΔZ) around the time of the Carrington storm. On their basis, we have chronologically revised the interplanetary coronal mass ejection transit time as ≤17.1 hr and located the ΔH peak at 06:20—06:25 UT, revealing a magnitude discrepancy between the hourly and spot measurements (−1691 nT versus −1263 nT). Furthermore, we have newly derived the time series of ΔY and ΔZ, which peaked at ΔY ≈ 378 nT (05:50 UT) and 377 nT (06:25 UT), and ΔZ ≈ −173 nT (06:40 UT). We have also computed their hourly averages and removed their solar quiet field variations in each geomagnetic component to derive their hourly disturbance variations (Dist) with latitudinal weighting. Our calculations have resulted in disturbance variations with latitudinal weighting of Dist Y ≈ 328 nT and Dist Z ≈ −36 nT, and three scenarios of Dist H ≈ −918, −979, and −949 nT, which also approximate the minimum Dst. These data may suggest preconditioning of the geomagnetic field after the August storm (ΔH ≤ −570 nT), which made the September storm even more geoeffective.

The Earth’s magnetic field displays variations on a broad range of time scales, from years to hundreds of millions of years. The last two decades of global and continuous satellite geomagnetic field monitoring have considerably enriched the knowledge on the rapid physical processes taking place in the Earth’s outer core. Identification of axisymmetric torsional Alfvén waves with subdecadal periods from observatory and satellite data has given access to an averaged intensity of the magnetic field in the Earth’s core interior. A significant part of the rapid signal, however, resides in nonaxisymmetric motions. Their origin has remained elusive, as previous studies of magnetohydrodynamic waves in the Earth’s core mainly focused on their possible signature on centennial time scales. Here, we identify nonaxisymmetric wavelike patterns in the equatorial region of the core surface from the observed geomagnetic variations. These wavelike features have large spatial scales, interannual periods in the vicinity of 7 y, amplitudes reaching 3 km/y, and coherent westward drift at phase speeds of about 1,500 km/y.We interpret and model these flows as the signature of Magneto–Coriolis (MC) eigenmodes. Their identification offers a way to probe the cylindrical radial component of the magnetic field inside Earth’s core. It follows from our work that there is no need for a stratified layer at the top of the core to account for the rapid geomagnetic field changes.

Observations of the geomagnetic field taken at Earth’s surface are processed to construct a set of continuous models of the geomagnetic field and its secular variation from 1956 to 2033. One of these models, the parent model, provides candidate main field models for the epochs 2020 and 2025 to the 14th generation of the International Geomagnetic Reference Field (IGRF). The secular variation candidate model for the period 2025–2030 is derived from a forecast of the secular variation in 2027.5, which results from a multi-variate singular spectrum analysis of the secular variation from 1960 to 2023. Apart from the parent model, we also derive models to higher spherical harmonic degrees than ℓ = 14 to study small-scale features of the core field and its temporal variation. A comparison with a satellite-based field model indicates a good agreement for the core field, but shows significant differences for the secular variation, which probably could be explained by the different source geometry of the data. Our results suggest a strengthening of the meridional core flow in recent years and the existence of north–south oriented undulations in the radial component of the secular variation which may be related to the presence of waves in Earth’s liquid outer core. Graphical Abstract

This study presents results of mapping three-dimensional (3-D) variations of the electrical conductivity in depths ranging from 400 to 1200 km using 6 years of magnetic data from the Swarm and CryoSat-2 satellites as well as from ground observatories. The approach involves the 3-D inversion of matrix Q-responses (transfer functions) that relate spherical harmonic coefficients of external (inducing) and internal (induced) origin of the magnetic potential. Transfer functions were estimated from geomagnetic field variations at periods ranging from 2 to 40 days. We study the effect of different combinations of input data sets on the transfer functions. We also present a new global 1-D conductivity profile based on a joint analysis of satellite tidal signals and global magnetospheric Q-responses.