Signs of a new geomagnetic jerk between 2019 and 2020 from Swarm and observatory data

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Following the observed pattern of a new geomagnetic jerk every 3–4 years, certain predictions suggested that a new event should occur around 2020 after the one observed around 2017.5. In this work, we explore this scenario by ana lysing the secular variation of the East geomagnetic feld component in both ground and satellite geomagnetic data. At ground, we use the available data from 2015 to 2021 in 10 observatories worldwide distributed. This analysis shows the occurrence of the mentioned jerk in mid-2017 at observatories located in the Pacifc region, but also reveals a new jerk between mid-2019 and early 2020 with a clear global character. Swarm satellite data also corroborate these fndings by means of the secular variation estimated using virtual observatories at 440 km altitude. In addition, a general view using the most recent CHAOS geomagnetic model confrms the global character of the 2020-jerk with V-shaped secular variation changes in meridional sectors covering the Eastern Pacifc, America, Asia and the Indian Ocean; and Λ-shapes in Europe, Africa and Western Pacifc. The radial geomagnetic feld at the core–mantle bound ary is investigated as the origin of the new jerk. Results show that the global-average secular acceleration of the radial feld exhibits a new pulse at mid-2018, establishing the starting epoch of the 2020-jerk.
© The Author(s) 2021. The authors are grateful to the Spanish research project PGC2018-099103A-I00 of the Spanish Ministry of Science, Innovation and Universities. The research that led to these results was also in part carried out using funds from "la Caixa" Foundation. SAC thanks to Juan de la Cierva Formación Program (FJC2018-037643-I). We would like to thank two anonymous reviewers for their constructive comments, which signifcantly improved our manuscript. This work has used geomagnetic observatory data and we thank all the research institutions and observatories that provide these data, most of them sup ported by the INTERMAGNET network. We also thank ESA for providing the Swarm Level-1b data.
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