ArchKalmag14k: A Kalman‐Filter Based Global Geomagnetic Model for the Holocene

Abstract

Global field reconstructions of the past are a key tool for understanding the dynamics of the Earth's magnetic field and the underlying processes in the Earth's core (e.g., Constable & Korte, 2015). This includes studying the evolution of field features, such as dipole decay, the South Atlantic Anomaly (SAA) and flux patches (Hartmann & Pacca, 2009;Jackson & Finlay, 2015). In the past, several techniques for constructing global field models have been developed and employed. Truncated spherical harmonics (SH) in the spatial domain combined with spline interpolation in time are widely used (Jackson et al., 2000;Korte et al., 2009). In the eighties, Constable and Parker (1988) first proposed using Gaussian processes to model the field dynamics, but until recently, the technique had not been applied to global field modeling. Only in the last years, statistical methods implementing this approach have been suggested (Hellio & Gillet, 2018;Nilsson & Suttie, 2021).Even though Bloxham and Jackson (1992) already discussed the accurate assessment of uncertainties, most following studies did not pursue the suggested analytical approaches, and either did not report uncertainties at

Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomaly

“…Despite the considerable progress that has been made over the past two decades, significant differences between different Holocene geomagnetic field models remain. Neither the recent dipole decay nor the appearance of SAA-type field asymmetries appear to be unusual features of the ancient geomagnetic field ( 15 – 17 ), but it is currently not clear if the former is always associated with the latter. Several studies have also suggested that the South Atlantic may represent a region of unusual field behavior ( 18 , 19 ).…”

Reconstituição do campo geomagnético para o Holoceno a partir de um espeleotema do Brasil Central

“…os círculos vermelhos são as amostras deste estudo. ____________________________________________________________ 42 2014) e ArchKalmag14k (Schanner et al, 2022). Extraído da base de Distribuição dos dados de dados GEOMAGIA (Brown et al, 2015).…”

“…Todos os modelos, exceto o modelo mais atualizado ArchKalmag (Schanner et al, 2022), apresentam uma tendência de campo mais fraco por volta dos 6 a 7 mil anos e uma variação de alta por volta dos 9 mil anos. É possível que estas variações maiores estejam mais associadas a variações no campo dipolar do que de campos não-dipolares.…”

“…É possível que estas variações maiores estejam mais associadas a variações no campo dipolar do que de campos não-dipolares. 2014) e ArchKalmag14k (Schanner et al, 2022). Extraído da base de Distribuição dos dados de dados GEOMAGIA (Brown et al, 2015).…”

“…Figura 30 -Distribuição dos dados de paleointensidade utilizados nos modelos. (a) HFMOL1.A1 e CALS10k.2 (Constable, 2016); (b) pfm9k.1a (Nilsson et al, 2015); (c) SHA.DIF.14k (Pavón-Carrasco et al,2014) e ArchKalmag14k(Schanner et al, 2022). Extraído da base de Distribuição dos dados de dados GEOMAGIA(Brown et al, 2015).…”