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© 2021 The Authors. SAC acknowledges The Living Planet Fellowship (TEMPO project) from ESA for providing financial support to this research. SAC and ADS also acknowledge ASI Limadou-Science Project for supporting this work partially. AGL acknowledges the grant FPU17/03635 from the Spanish Ministry of Education. FJPC is grateful to the Spanish research project PGC2018-099103-A-I00. All data and models used to carry out this work can be found in the associated references and in the repository of DTU Space (http://www.space.dtu.dk/english/Research/Scientific_data_and_models/Magnetic_Field_Models). The authors are very grateful to Editor and two reviewers for their useful comments that have helped to improve the quality of this manuscript., Geomagnetic jerks are sudden changes in the geomagnetic field secular variation related to changes in outer core flow patterns. Finding geophysical phenomena related to geomagnetic jerks provides a vital contribution to better understand the geomagnetic field behavior. Here, we link the geomagnetic jerks occurrence with one of the most relevant features of the geomagnetic field nowadays, the South Atlantic Anomaly (SAA), which is due to the presence of reversed flux patches (RFPs) at the Core-Mantle Boundary (CMB). Our results show that minima of acceleration of the areal extent of SAA calculated using the CHAOS-7 model (CHAOS-7.2 release) coincide with the occurrence of geomagnetic jerks for the last 2 decades. In addition, a new pulse in the secular acceleration of the radial component of the geomagnetic field has been observed at the CMB, with a maximum in 2016.2 and a minimum in 2017.5. This fact, along with the minimum observed in 2017.8 in the acceleration of the areal extent of SAA, could point to a new geomagnetic jerk. We have also analyzed the acceleration of the areal extent of South American and African RFPs at the CMB related to the presence of the SAA at surface and have registered minima in the same periods when they are observed in the SAA at surface. This reinforces the link found and would indicate that physical processes that produce the RFPs, and in turn the SAA evolution, contribute to the core dynamics at the origin of jerks., Ministerio de Ciencia e Innovación (MICINN), Ministerio de Educación, Cultura y Deporte (MECD), The Living Planet Fellowship from ESA, ASI Limadou-Science Project, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

The debated question on the possible relation between the Earth’s magnetic field and climate has been usually focused on direct correlations between different time series representing both systems. However, the physical mechanism able to potentially explain this connection is still an open issue. Finding hints about how this connection could work would suppose an important advance in the search of an adequate physical mechanism. Here, we propose an innovative information-theoretic tool, i.e. the transfer entropy, as a good candidate for this scope because is able to determine, not simply the possible existence of a connection, but even the direction in which the link is produced. We have applied this new methodology to two real time series, the South Atlantic Anomaly (SAA) area extent at the Earth’s surface (representing the geomagnetic field system) and the Global Sea Level (GSL) rise (for the climate system) for the last 300 years, to measure the possible information flow and sense between them. This connection was previously suggested considering only the long-term trend while now we study this possibility also in shorter scales. The new results seem to support this hypothesis, with more information transferred from the SAA to the GSL time series, with about 90% of confidence level. This result provides new clues on the existence of a link between the geomagnetic field and the Earth’s climate in the past and on the physical mechanism involved because, thanks to the application of the transfer entropy, we have determined that the sense of the connection seems to go from the system that produces geomagnetic field to the climate system. Of course, the connection does not mean that the geomagnetic field is fully responsible for the climate changes, rather that it is an important driving component to the variations of the climate.

The Earth’s magnetic field is characterized by different temporal chaotic fluctuations such as reversals, excursions, archeomagnetic and geomagnetic jerks. During the last decades the number of geomagnetic jerks has increased up to recent rates of one jerk every 3 years. In addition, the dipolar field is continuously decreasing since the time we had geomagnetic instrumental or historical measurements and the non-dipolar harmonic contributions are taking an important role in the present geomagnetic field behaviour, as reflected by the rapid growth of the region covered by the South Atlantic Anomaly. These mentioned facts seem to indicate that something is changing in the Earth’s outer core where the main part of the geomagnetic field has its origin, pointing out a possible imminent reversal or excursion. In this work we analyse with different techniques the occurrence of this geomagnetic changes during the last decades, paying attention to the most recent years, thanks to the most accurate geomagnetic data provided by the ESA’s Swarm satellite mission