Abstract
Changes in the state of the D and E ionospheric regions lead to variations in the amplitude-phase characteristics of VLF radio signals. The existing theoretical and empirical models of the propagation of low-frequency electromagnetic waves qualitatively describe the relative variations in the parameters of the lower ionosphere associated with strong heliogeophysical disturbances; however, these models do not allow estimation of the absolute value and distribution of the electron concentration. We used the measurement data for the amplitude-phase characteristics of VLF radio signals with different frequencies propagating along two closely spaced paths. This made it possible not only to quantify the parameters of the D region of the ionosphere on a spatial scale of thousands of kilometers during the powerful solar flare of September 10, 2017 but also to restore the electron concentration profile before the onset of X-ray radiation.
Similar content being viewed by others
REFERENCES
Basak, T. and Chakrabarti, S.K., Effective recombination coefficient and solar zenith angle effects on low-latitude D-region ionosphere evaluated from VLF signal amplitude and its time delay during X-ray solar flares, Astrophys. Space Sci., 2013, vol. 348, pp. 315–326. https://doi.org/10.1007/s10509-013-1597-9
Clilverd, M.A., Seppala, A., Rodger, C.J., Thomson, N.R., Verronen, P.T., Turunen, E., Ulich, T., Lichtenberger, J., and Steinbach, P., Modeling polar ionospheric effects during the October–November 2003 solar proton events, Radio Sci., 2006, vol. 41, RS2001. https://doi.org/10.1029/2005RS003290
Ferguson, J.A., Ionospheric model validation at VLF and LF, Radio Sci., 1995, vol. 30, no. 3, pp. 775–782.
Ferguson, J.A., Computer Programs for Assessment of Long-Wavelength Radio Communications, Version 2.0, Technical document 3030, San Diego: Space and Naval Warfare Systems Center, 1998.
Friedrich, M., Pock, C., and Torkar, K., FIRI-2018, an updated empirical model of the lower ionosphere, J. Geophys. Res.: Space, 2018, vol. 123, pp. 6737–6751.
Gavrilov, B.G., Zetser, Yu.I., Ryakhovskii, I.A., Poklad, Yu.V., and Ermak, V.M., Remote sensing of ELF/VLF radiation induced in experiments on artificial modification of the ionosphere, Geomagn. Aeron. (Engl. Transl.), 2015, vol. 55, no. 4, pp. 450–456.
Gavrilov, B.G., Zetser, Yu.I., Lyakhov, A.N., Poklad, Yu.V., and Ryakhovskii, I.A., Correlated disturbances of the upper and lower ionosphere from synchronous measurements of parameters of GNSS signals and VLF radio signals, Cosmic Res., 2019, vol. 57, no. 1, pp. 36–43.
Hayakawa, M., Molchanov, O.A., Ondoh, T., and Kawai, E., The precursory signature effect of the Kobe earthquake on VLF subionospheric signals, J. Commun. Res. Lab., 1996, vol. 43, pp. 169–180.
Klobuchar, J.A. and Whitney, H.E., Ionospheric electron content measurements during a solar eclipse, J. Geophys. Res., 1965, vol. 70, pp. 1254–1257.
Kozlov, S.I., Lyakhov, A.N., and Bekker, S.Z., Key principles of constructing probabilistic statistical ionosphere models for the radiowave propagation problems, Geomagn. Aeron. (Engl. Transl.), 2014, vol. 54, no. 6, pp. 750–762.
Mitra, A.P., Ionospheric Effects of Solar Flares, Dordrecht: D. Reidel, 1974.
Peter, W.B., Chevalier, M.W., and Inan, U.S., Perturbations of midlatitude subionospheric VLF signals associated with lower ionospheric disturbances during major geomagnetic storms, J. Geophys. Res., 2006, vol. 111, A03301. https://doi.org/10.1029/2005JA011346
Rodger, C.J., Red sprites, upward lightning, and VLF perturbations, Rev. Geophys., 1999, vol. 37, pp. 317–336.
Singh, A.K., Singh, R., Veenadhari, B., and Singh, A.K., Response of low latitude D-region ionosphere to the total solar eclipse of 22 July 2009 deduced from ELF/VLF analysis, Adv. Space Res., 2012, vol. 50, pp. 1352–1361. https://doi.org/10.1016/j.asr.2012.07.005
Tanaka, Y.T., Raulin, J.P., Bertoni, F.C.P., Fagundes, P.R., Chau, J., Schuch, N.J., Hobara, Y., Terasawa, T., and Takahashi, T., First very low frequency detection of short repeated bursts from magnetar SGR J1550-5418, Astrophys. J. Lett., 2010, vol. 721, no. 1, pp. 24–27.
Thomson, N.R., Daytime tropical D region parameters from short path VLF phase and amplitude, J. Geophys. Res., 2010, vol. 115, A09313. https://doi.org/10.1029/2010JA015355
Thomson, N.R., Rodger, C.J., and Dowden, R.L., Ionosphere gives size of greatest solar flare, Geophys. Res. Lett., 2004, vol. 31, L06803. https://doi.org/10.1029/2003GL019345
Thomson, N.R., Rodger, C.J., and Clilverd, M.A., Large solar flares and their ionospheric D region enhancements, J. Geophys. Res., 2005, vol. 110, A06306. https://doi.org/10.1029/2005JA011008
Thomson, N.R., Rodger, C.J., and Clilverd, M.A., Daytime D region parameters from long-path VLF phase and amplitude, J. Geophys. Res., 2011, vol. 116, A11305. https://doi.org/10.1029/2011JA016910
Wait, J.R. and Spies, K.P., Characteristics of the Earth–ionosphere waveguide for VLF radio waves, NBS Technical Note 300, 1964.
Funding
The study was performed as part of the state assignment АААА-А17-117112350014-8.
Author information
Authors and Affiliations
Corresponding authors
Additional information
Translated by M. Chubarova
Rights and permissions
About this article
Cite this article
Gavrilov, B.G., Ermak, V.M., Poklad, Y.V. et al. Estimate of Variations in the Parameters of the Midlatitude Lower Ionosphere Caused by the Solar Flare of September 10, 2017. Geomagn. Aeron. 59, 587–592 (2019). https://doi.org/10.1134/S0016793219050049
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S0016793219050049