Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

High frequency sky wave propagation during geomagnetic field reversals

  • 11 Accesses


The ionosphere, a plasma embedded in the Earth’s magnetic field, affects propagation of electromagnetic waves in the high frequency range since the refractive index at these frequencies depends on a combination of plasma density and magnetic field intensity and direction. In particular, the ground range of high frequency waves that reflect in the ionosphere, or sky waves, presents detectable Earth’s magnetic field effects. This field varies greatly, with the most drastic scenario being a polarity reversal. The spatial variability of the ground range during possible reversal scenarios is analyzed in the present work using numerical ray tracing. In order to isolate the magnetic field effect we exclude the effect of changing ionospheric conditions by considering a uniform ionosphere. Our results show that the ground range increases with increasing ray alignment with the field direction as well as with increasing magnetic field intensity. For the present field that is dominated by an axial dipole, the ground range is greatest for northward propagation at the magnetic equator. A similar situation occurs for a prevailing equatorial dipole with eastward propagation at the corresponding magnetic equator that here runs almost perpendicular to the geographic equator. For less dipolar configurations the ground range spatial variability becomes smaller. Although a reversal is foreseeable only in a very distant future, studying potential consequences during a reversal may highlight possible effects of dipole decrease which is already ongoing at present. In addition to the geophysical insight, our results may have applications for communication and radar systems.

This is a preview of subscription content, log in to check access.


  1. Amit H. and Olson P., 2010. A dynamo cascade interpretation of the geomagnetic dipole decrease. Geophys. J. Int., 181, 1411–1427.

  2. Amit H., Leonhardt R. and Wicht J., 2010. Polarity reversals from paleomagnetic observations and numerical dynamos simulations. Space Sci. Rev., 155, 293–335.

  3. Amit H., Choblet G., Olson P., Monteux J., Deschamps F., Langlais B. and Tobie G., 2015. Towards more realistic core-mantle boundary heat flux patterns: a source of diversity in planetary dynamos. Prog. Earth Planet. Sci., 2, 22–26.

  4. Aubert J., 2005. Steady zonal flows in spherical shell fluid dynamos. J. Fluid Mech., 542, 53–67.

  5. Azzarone A., Bianchi C., Pezzopane M., Pietrella M., Scotto C. and Settimi, A., 2012. IONORT: A Windows software tool to calculate the HF ray tracing in the ionosphere. Comput. Geosci., 42, 57–63.

  6. Backus G.E. and Bullard C., 1968. Kinematics of geomagnetic secular variation in a perfectly conducting core. Philos. Trans. R. Soc. A-Math. Phys. Eng. Sci., 263, 239–266.

  7. Bilitza D., 2018. IRI the international standard for the ionosphere. Adv. Radio Sci., 16, 1–11.

  8. Cao H., Yadav R.K. and Aurnou J.M., 2018. Geomagnetic polar minima do not arise from steady meridional circulation. Proc. Nat. Acad. Sci. USA, 115, 11186–11191.

  9. Clement B.M., 2004. Dependence of the duration of geomagnetic polarity reversals on site latitude. Nature, 428, 637–640.

  10. Cnossen I., Richmond A.D., Wiltberger M., Wang W. and Schmitt P., 2011. The response of the coupled magnetosphere-ionosphere-thermosphere system to a 25% reduction in the dipole moment of the Earth’s magnetic field. J. Geophys Res.-Space Phys., 116, A12304.

  11. Dao E.V., McNamara L.F. and Colman J.J., 2016. Magnetic field effects on the accuracy of ionospheric mirror models for geolocation. Radio Sci., 51, 284–300.

  12. Davies K., 1965. Ionospheric Radio Propagation. National Bureau of Standards Monograph 80. U.S. Dept. of Commerce, Washington, D.C.

  13. Finlay C.C., 2008. Historical variation of the geomagnetic axial dipole. Phys. Earth Planet. Inter., 170, 1–14.

  14. Finlay C.C. and Amit H., 2011. On flow magnitude and field-flow alignment at Earth’s core surface. Geophys. J Int., 186, 175–192.

  15. Finlay C.C., Aubert J. and Gillet N., 2016. Gyre-driven decay of the Earth’s magnetic dipole. Nat. Commun., 7, 10422.

  16. Glassmeier K.H., Soffel H. and Negendank J.F.W., 2009. Geomagnetic Field Variations. Springer Verlag, Berlin, Germany.

  17. Haselgrove J., 1955. Ray theory and a new method for ray tracing. Physics of the Ionosphere. The Physical Society, London, U.K., 355–364.

  18. Hernández-Pajares M., Juan J.M., Sanz J. and Orús R., 2007. Second-order ionospheric term in GPS: Implementation and impact on geodetic estimates. J. Geophys Res.-Solid Earth, 112, B08417.

  19. Hoque M.M. and Jakowski N., 2008. Estimate of higher order ionospheric errors in GNSS positioning. Radio Sci., 43, RS5008.

  20. Huguet L. and Amit H., 2012. Magnetic energy transfer at the top of Earth’s core. Geophys. J. Int., 190, 856–870.

  21. Huguet L., Amit H. and Alboussière T., 2018. Geomagnetic dipole changes and upwelling/downwelling at the top of the Earth’s core. Front. Earth Sci., 6, UNSP 170.

  22. IPCC, 2014. Climate Change 2014. Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland.

  23. Jacobs J.A., 1994. Reversals of the Earth’s Magnetic Field. Cambridge University Press, Cambridge, U.K.

  24. Jones R.M. and Stephenson J.J., 1975. A Versatile Three-Dimensional Ray Tracing Computer Program for Radio Waves in the Ionosphere. Office of Telecommunications Report 75–76. U.S. Department of Commerce, Washington, D.C.

  25. Lowes F.J., 1974. Spatial power spectrum of the main geomagnetic field, and extrapolation to the core. Geophys. J. R. Astron. Soc., 36, 717–730.

  26. Merrill R.T., McElhinny M.W. and McFadden P.L., 1998. The Magnetic Field of the Earth. Academic Press, San Diego, CA.

  27. Millington G., 1951. The effect of the Earth’s magnetic field on short-wave communication by the ionosphere. Proc. IEE — Part III: Radio Commun. Eng., 98, 314–319, DOI: https://doi.org/10.1049/pi-3.1951.0064.

  28. Olson P. and Amit H., 2006. Changes in Earth’s dipole. Naturwissenschaften, 93, 519–542.

  29. Olson P. and Amit H., 2015. Mantle superplumes induce geomagnetic superchrons. Front. Earth Sci., 3, UNSP 38.

  30. Peña D., Amit H. and Pinheiro K.J., 2016. Magnetic field stretching at the top of the shell of numerical dynamos. Earth Planets Space, 68, 78.

  31. Petrie E.J., Hernández-Pajares M., Spalla P., Moore P. and King M.A., 2011. A review of higher order ionospheric refraction effects on dual frequency GPS. Surv. Geophys., 32, 197–253.

  32. Rao N.N., 1969. Bearing deviation in high-frequency transionospheric propagation: 3. Ray tracing investigation of the magnetoionic effect. Radio Sci., 4, 153–161.

  33. Settimi A. and Bianchi S., 2014. Ray theory formulation and ray tracing method. Application in ionospheric propagation. Quaderni di Geofisica, N°121, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.

  34. Thébault E., Finlay C.C., Beggan C., Alken P., Aubert J., et al., 2015. International Geomagnetic Reference Field: the 12th generation. Earth Planets Space, 67, 79.

  35. Tsai L.C., Liu C.H. and Huang J.Y., 2010. Three-dimensional numerical ray tracing on a phenomenological ionospheric model. Radio Sci., 45, RS5017.

  36. Valet J.P. and Fournier A., 2016. Deciphering records of geomagnetic reversals. Rev. Geophys., 54, 410–446.

  37. Zossi B.S., Elias A.G. and Fagre M., 2018. Ionospheric conductance spatial distribution during geomagnetic field reversals. J. Geophys Res.-Space Phys., 123, 2379–2397.

  38. Zossi B.S., Fagre M., Amit H. and Elias A.G., 2019. Polar caps during geomagnetic polarity reversals. Geophys. J. Int., 216, 1334–1343.

Download references


We thank Anna Belehaki for constructive comments that improved the paper.

Author information

Correspondence to Ana G. Elias.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Fagre, M., Zossi, B.S., Yiğit, E. et al. High frequency sky wave propagation during geomagnetic field reversals. Stud Geophys Geod 64, 130–142 (2020). https://doi.org/10.1007/s11200-019-1154-2

Download citation


  • ray tracing
  • radiowave propagation
  • Earth’s magnetic field
  • paleomagnetism