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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Geomagnetic jerk features produced using synthetic core flow models

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Author(s):
Pinheiro, K. J. [1, 2] ; Amit, H. [1] ; Terra-Nova, F. [3, 1]
Total Authors: 3
Affiliation:
[1] Nantes Atlantiques Univ, Univ Nantes, CNRS, Lab Planetol & Geodynam, UMR 6112, 2 Rue Houssiniere, F-44000 Nantes - France
[2] Observ Nacl, Geophys Dept, BR-20921400 Rio De Janeiro - Brazil
[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Geofis, Rua Matao 1226, BR-05508090 Sao Paulo - Brazil
Total Affiliations: 3
Document type: Journal article
Source: PHYSICS OF THE EARTH AND PLANETARY INTERIORS; v. 291, p. 35-53, JUN 2019.
Web of Science Citations: 0
Abstract

Geomagnetic jerks are the shortest temporal variations of the magnetic field generated in the Earth's core. The physical mechanism producing such abrupt changes as well as their spatio-temporal characteristics are not well understood. In order to explore geomagnetic jerks generation and their characteristics, we use a set of synthetic core flow models to solve the radial magnetic induction equation. We analyze changes of trend in the secular variation time series using a cubic polynomial fit, by invoking a new formalism of jerk amplitude per unit duration time. A new visualization scheme allows interpreting jerk amplitudes and occurrences in space and time. We find that a mild time-dependence of flow amplitude, while keeping a fixed pattern, reproduces geomagnetic jerk amplitudes. The polynomial fits were compared with two line-segments fits at ten sampled magnetic observatories about historical jerk occurrences. The differences between the misfits in the two approaches are small, which may question the definition of geomagnetic jerks as sharp ``V-shape{''}. The local time series in our models exhibit secular acceleration changes of sign that reproduce some main observed characteristics of geomagnetic jerks: (i) a range of amplitudes that encompass those observed in geomagnetic jerks, (ii) non-simultaneous occurrence, (iii) non-global occurrence, (iv) spatial variability of amplitudes and (v) strongest amplitudes in the radial component. (AU)

FAPESP's process: 18/07410-3 - Persistence of the South Atlantic Anomaly in geomagnetic observations, field models and numerical dynamos
Grantee:Filipe Terra Nova dos Santos
Support Opportunities: Scholarships in Brazil - Post-Doctoral