Geomagnetic core field models and secular variation forecasts for the 13th International Geomagnetic Reference Field (IGRF-13)

Wardinski, Ingo; Saturnino, Diana; Amit, Hagay; Chambodut, Aude; Langlais, B.; Mandea, Mioara; Thébault, Erwan

doi:10.21203/rs.3.rs-26497/v2

Cited by 2 publications

(3 citation statements)

References 34 publications

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“…Based on the analysis and modeling results of observed data over the last 400 years and archeomagnetic studies, the radial field at the CMB has generally displayed opposite morphologies in the Northern Hemisphere (negative) and Southern Hemisphere (positive; Korte & Holme, 2010). However, some subflux systems show a sign opposite to that of their hemisphere (such as the southern Atlantic anomaly), while others are normal (Stefan et al., 2017; Terra‐Nova et al., 2015; Wardinski et al., 2020). For both subflux systems, the intensity and location are always migrating.…”

Section: Introductionmentioning

confidence: 99%

Paleosecular Variations During the Last Glacial Period From Tengchong Qinghai Lake, Yunnan Province, China

Yang

Zhang

et al. 2022

JGR Solid Earth

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In recent years, the evolution of the magnetic flux lobes in terms of location and intensity has been attributed to paleosecular variation of the geomagnetic field, reflecting outer‐core fluid convection close to the core‐mantle boundary. However, most results were based on observational data for the past 400 years supplemented by sparse archeomagnetic studies with data for approximately 3 kyr. In this paper, we construct a relative paleointensity (RPI) record and an inclination record spanning the past ∼90 kyr based on two cores from Tengchong Qinghai Lake (Yunnan Province, China), a closed crater lake that formed in the late Pleistocene. The evolution of flux lobes and the non‐dipole field can be assessed on a much longer time scale. Although the concentration and domain state of magnetic grains in the cores vary significantly, the RPI record is still representative of geomagnetic field features in the region of Yunnan Province, China. The contrasting trends in RPI with the records for eastern China since the late Holocene indicate the southeastward migration of the Siberian flux lobe. During the last glacial period, the RPI records of Tengchong Qinghai Lake and the North Atlantic Ocean show opposite trends, denoting the diverse and strong influence of the two flux lobe systems. The strong reverse flux lobe in the North Atlantic Ocean strengthened the non‐dipole field, while the weak normal flux lobe in Tengchong weakened the non‐dipole field.

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Section: Introductionmentioning

confidence: 99%

Paleosecular Variations During the Last Glacial Period From Tengchong Qinghai Lake, Yunnan Province, China

Yang

Zhang

et al. 2022

JGR Solid Earth

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“…For the main field at epochs 2015.0 and 2020.0, some teams derived their candidate models from parent models describing the magnetic field over multi-decadal periods by combining datasets from several satellite missions and ground observatories (Finlay et al, 2020;Huder et al, 2020;Ropp et al, 2020;Sabaka et al, 2020;Wardinski et al, 2020). Several teams built parent models covering the full Swarm satellite mission era (November 2013 to present) (Brown et al, 2020;Rother et al, 2020;Vigneron et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…For the predictive secular variation models covering 2020.0 to 2025.0, the candidates broadly fall into two main categories: (1) computing SV solely from the latest available satellite and ground data (Alken et al, 2020a;Finlay et al, 2020;Huder et al, 2020;Pavón-Carrasco et al, 2020;Petrov and Bondar, 2020;Rother et al, 2020), or (2) applying physics-based modeling, combined with recent satellite and ground data to forecast future field changes based on underlying core dynamics (Brown et al, 2020;Fournier et al, 2020;Metman et al, 2020;Minami et al, 2020;Sanchez et al, 2020;Tangborn et al, 2020;Wardinski et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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

Alken

Thébault

Beggan

et al. 2020

Preprint

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

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Geomagnetic core field models and secular variation forecasts for the 13th International Geomagnetic Reference Field (IGRF-13)

Cited by 2 publications

References 34 publications

Paleosecular Variations During the Last Glacial Period From Tengchong Qinghai Lake, Yunnan Province, China

Paleosecular Variations During the Last Glacial Period From Tengchong Qinghai Lake, Yunnan Province, China

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

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