Earth, Planets and Space

, Volume 59, Issue 7, pp 675–684 | Cite as

Geomagnetic jerks from the Earth’s surface to the top of the core

  • Aude Chambodut
  • Céline Eymin
  • Mioara Mandea
Open Access
Article

Abstract

Rapid changes in the magnetic field characterised by an abrupt change in the secular variation have been named “secular variation impulses” or “geomagnetic jerks”. Three of these events, around 1968, 1978 and 1990, occurred during the time-span covered by the comprehensive model CM4 (Sabaka et al., 2002, 2004). This model, providing the best temporal resolution between 1960 and 2002 as well as a fine separation of the different magnetic sources, can be used to study rapid phenomena of internal origin. In order to analyse these events all over the globe, synthetic time series were obtained from the CM4 model between 1960–2002. Geomagnetic jerks are detected here as a rapid movement of the zero isoline of the second field derivative. Analysis of the area swept out by this isoline as a function of time allows us to map the spatial extent of jerks though time, and to identify an event around 1985 that is localized in the Pacific area. At the core surface, we compute the fluid flows under the frozen-flux and tangentially geostrophic assumptions. The flows do not exhibit any special pattern at jerk times, but instead show a smooth temporal evolution over the whole time period. However, the mean amplitude of the dynamical pressure associated with these flows present maxima at each jerk occurrence and helps to confirm the identification of a jerk in 1985.

Key words

Geomagnetic jerks magnetic models core surface flows core dynamics 

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Copyright information

© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2007

Authors and Affiliations

  • Aude Chambodut
    • 1
    • 2
  • Céline Eymin
    • 3
  • Mioara Mandea
    • 2
  1. 1.Department of Applied and Industrial MathematicsUniversity of PotsdamPotsdamGermany
  2. 2.GeoForschungsZentrum PotsdamTelegrafenbergPotsdamGermany
  3. 3.Laboratoire de Géophysique Interne et TectonophysiqueUniversité Joseph FourierGrenoble Cedex 9France

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