Geomagnetic Secular Variation and Its Applications to the Core

Andrew Jackson, Chris Finlay

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We review the observational constraints on the morphology and evolution of the magnetic field of the Earth over the last few centuries; these changes are referred to as the secular variation.Starting with a description of the available sources of original observations of the field, we thendiscuss the mathematical models of the field’s evolution that can be derived from them. We discussthe prominent features of the field’s evolution, both at the Earth’s surface and at the surface of theliquid core. The final section concerns itself with a discussion of the interpretation of the field’sevolution, in terms of physical core processes. These divide themselves into processes associatedwith movement of core fluid, which is capable of advecting the field, and processes associated withthe finite resistivity of the core, commonly termed diffusive processes. We lay the foundations for some of the more theoretical subjects covered in Volume Eight.
Original languageEnglish
Title of host publicationTreatise on Geophysics : Geomagnetism
Editors Gerald Schubert
Publication date2015
ISBN (Print)978-0444538024
Publication statusPublished - 2015


  • Earth’s core
  • Geomagnetism
  • Secular variation
  • Magnetohydrodynamics
  • Magnetic field
  • Geomagnetic secular variation
  • Geomagnetic observations

Cite this

Jackson, A., & Finlay, C. (2015). Geomagnetic Secular Variation and Its Applications to the Core. In G. Schubert (Ed.), Treatise on Geophysics: Geomagnetism (2nd ed., Vol. 5, pp. 137-184). Elsevier.