Geomagnetic jerk features produced using synthetic core flow models

Autor(es)

Pinheiro, K. J. ^{[1, 2]} ; Amit, H. ^[1] ; Terra-Nova, F. ^{[3, 1]}

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: PHYSICS OF THE EARTH AND PLANETARY INTERIORS; v. 291, p. 35-53, JUN 2019.
• Citações Web of Science: 0

Resumo

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)

• Processo FAPESP: 18/07410-3 - Persistência da Anomalia do Atlântico Sul em observações e modelos do campo geomagnético e simulações numéricas do dínamo
• Beneficiário: Filipe Terra Nova dos Santos
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado