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MHD Sources, 1600-2005 Evolution and 1900-2005 Probabilistic Time Analysis for Logarithmic Time-Derivatives of Geomagnetic Spherical Harmonics

  • S. V. Starchenko
  • S. V. Yakovleva
Conference paper
Part of the Springer Geophysics book series (SPRINGERGEOPHYS)

Abstract

MHD sources of geomagnetic spherical harmonics are estimated via logarithmic time derivatives (or exponential rates) of Gauss components basing on IGRF and gufm1 models. 1600–2005 rates’ evolutions show long flat ‘quiet’ and short pick-shaped ‘disturbed’ fields. Our probabilistic time analysis identifies the probabilities to grow/decay, expected values for grow/decay and median rates together with periodicity/aperiodicity estimates. Total grow/decay variations are ~20 years and median variations are ~100 years with variation as an inverse rate. Since 1900, the quiet field has grow/decay variations ~30 years while disturbed fields’ grow/decay variations ~10 years. The median variations are ~60 years for disturbed field and ~200 years for quiet one.

Keywords

Time analysis Geomagnetic variations Spherical harmonics Geodynamo 

Notes

Acknowledgements

We are very grateful to anonymous reviewer who helped us to improve this work and we even inserted in our text three sentences of him/her. This work was partly supported by the Russian Foundation for Basic Research (project no. 16-05-00507a).

References

  1. Christensen U.R. Dynamo Scaling Laws and Applications to the Planets // Space Sci Rev. V.152. P. 565–590. 2010.Google Scholar
  2. Frick P.G. Turbulence: models and approaches. Lecture course (in Russian). Perm State Technical University. Part II. Perm. 1999. ISBN 5-88151-193-X.Google Scholar
  3. Jackson A., Jonkers A. R. T., Walker M. R. Four centuries of geomagnetic secular variation from historical records // Phil. Trans. R. Soc. Lond. V. A358. P. 957–990. 2000.Google Scholar
  4. Rhines P.B. Waves and turbulence on a beta plane // J. Fluid Mech. V. 69. P. 417–433. 1975.Google Scholar
  5. Starchenko S.V. Analytic base of geodynamo-like scaling laws in the planets, geomagnetic periodicities and inversions // Geomagnetism and Aeronomy. V. 54. No 6. P. 694–701. 2014.Google Scholar
  6. Starchenko, S.V., Observational estimate of magnetic field and geodynamo parameters under the surface of the Earth’s core // Geomagnetism and Aeronomy. V. 55. No 5. P. 712–718. 2015.Google Scholar
  7. Starchenko S.V., Jones C.A. Typical velocities and magnetic field strengths in planetary interiors // Icarus. V. 157. P. 426–435. 2002.Google Scholar
  8. Starchenko S.V., Pushkarev Y.D. Magnetohydrodynamic scaling of geodynamo and a planetary protocore concept // Magnetohydrodynamics. V. 49. No. 1. P. 35–42. 2013.Google Scholar
  9. Starchenko S.V., Yakovleva S.V. MHD sources of multipoles in the Earth’s core from 400 years of observations / Proceedings of the 11th International School and Conference “Problems of Geocosmos”. P. 109–115. 2016.Google Scholar
  10. Tijms H. Understanding Probability. 2nd edition. Cambridge University Press. 2007.Google Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave PropagationTroitsk, MoscowRussia

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