Geomagnetic jerk

In geophysics, a geomagnetic jerk or secular geomagnetic variation impulse is a relatively sudden change in the second derivative of the Earth's magnetic field with respect to time.[1]

These events were noted by Vincent Courtillot and Jean-Louis Le Mouël in 1976.[2][3] The clearest ones, observed all over the world, happened in 1969, 1978, 1991, and 1999. Data before 1969 is scarcer, but there is evidence of other global jerks in 1901, 1913, and 1925. Other events in 1932, 1949, 1958, 1986, and 2003 were detected only in some parts of the world.[1][4][5] These events are believed to originate in the interior of the Earth (rather than being due to external phenomena such as the solar wind); but their precise cause is still a matter of research.[5]

The name "jerk" was borrowed from kinematics, where it means the rate of change of the acceleration of a body, that is, the third derivative of its position with respect to time (the acceleration being the second derivative); or, more specifically, a sudden and momentary spike (or dip) in that rate.

  1. ^ a b De Michelis, Paola; Tozzi, Roberta; Meloni, Antonio (2005). "Geomagnetic jerks: observation and theoretical modeling" (PDF). Memorie della Società Astronomica Italiana. 76: 957–960. Retrieved 16 September 2019.
  2. ^ Courtillot, Vincent; Le Mouël, Jean-Louis (10 June 1976). "On the long-period variations of the Earth's magnetic field from 2 months to 20 years". Journal of Geophysical Research. 81 (17): 2941–2950. doi:10.1029/JB081i017p02941.
  3. ^ Courtillot, V.; Le Mouël, J. L. (October 1984). "Geomagnetic secular variation impulses". Nature. 311 (5988): 709–716. doi:10.1038/311709a0.
  4. ^ Cite error: The named reference mioara was invoked but never defined (see the help page).
  5. ^ a b Olsen, Nils; Mandea, Mioara (March 2007). "Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk". Earth and Planetary Science Letters. 255 (1–2): 94–105. doi:10.1016/j.epsl.2006.12.008.